Illinois · Monthly
September 2026
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1 Key messages and climate synopsis
Source: NOAA NCEI
Source: NOAA NCEI
2 Global and regional climate drivers
Sea-surface temperature anomaly, September 2026 (°C, 1991–2020)
Source: NOAA NCEI / PSL
Sea-surface temperature anomaly in the Niño regions (°C)
| Region | Anomaly (°C) | Change from preceding period (°C) |
|---|---|---|
| Niño 1+2 | 4.7 | 0.6 |
| Niño 3 | 3.6 | 0.5 |
| Niño 3.4 | 2.8 | 0.3 |
| Niño 4 | 0.9 | 0.0 |
Mean of the months in the period (OISST v2.1)
Source: NOAA CPC
El Niño conditions of very strong intensity: the Oceanic Niño Index (ONI) for JAS 2026 was +2.2 °C.
Source: NOAA CPC
Monthly Niño 3.4 anomaly, last 24 months (°C)
Source: NOAA CPC
MJO phase diagram (real-time OMI)
Source: NOAA PSL
Teleconnection indices
| Index | Value | Phase |
|---|---|---|
| NAO | 0.5 | Positive |
| AO | 1.2 | Positive |
| PDO | −1.6 | Negative |
North Atlantic Oscillation (NAO); Arctic Oscillation (AO); Pacific Decadal Oscillation (PDO).
Source: NOAA CPC, NOAA NCEI
The Niño 3.4 anomaly was +2.84 °C (+0.32 °C relative to the preceding period).
The MJO was active on 3 of 30 days, most often in phase 2 (Indian Ocean); mean amplitude 0.7.
Other indices: NAO +0.53 (positive phase); AO +1.16 (positive phase); PDO −1.55 (negative phase).
3 Precipitation
Source: NOAA NCEI
Accumulated precipitation
Source: NOAA NCEI
Percent of normal precipitation (1991–2020)
Source: NOAA NCEI
Percent of normal by county
Source: NOAA NCEI
Precipitation by region
| Region | Total (mm) | Normal (mm) | Difference (%) | Category |
|---|---|---|---|---|
| Northwest | 182.2 | 92.4 | 97.3 | Much above normal |
| Northeast | 127.2 | 86.2 | 47.6 | Above normal |
| West | 82.9 | 91.5 | −9.4 | Near normal |
| Central | 67.7 | 83.4 | −18.8 | Near normal |
| East | 65.9 | 81.0 | −18.6 | Near normal |
| West Southwest | 35.1 | 82.3 | −57.4 | Below normal |
| East Southeast | 38.7 | 80.8 | −52.2 | Below normal |
| Southwest | 29.3 | 82.7 | −64.6 | Much below normal |
| Southeast | 39.7 | 85.9 | −53.8 | Below normal |
Source: NOAA NCEI
Stations with the largest precipitation excess
| Region | County | Station | Altitude (m) | Anomaly (%) |
|---|---|---|---|---|
| Northwest | Lee | Paw Paw 2S | 271.0 | 192.7 |
| Northwest | Jo Daviess | Elizabeth | 206.0 | 188.6 |
| Northwest | Rock Island | Rock Is L&D 15 | 173.0 | 187.4 |
| Northeast | Kane | Chicago Aurora Muni AP | 214.0 | 171.1 |
| Northwest | Carroll | Mt Carroll | 216.0 | 142.7 |
| Northwest | Whiteside | Fulton L&D #13 | 180.0 | 132.8 |
| Northwest | Rock Island | Moline Quad City Intl AP | 176.0 | 122.0 |
| Northwest | Rock Island | Illinois City Dam 16 | 168.0 | 115.9 |
| Northeast | Kane | Aurora Water | 206.0 | 115.3 |
| Northwest | Winnebago | Rockford Gtr Rockford AP | 221.0 | 104.2 |
Source: NOAA NCEI
Stations with the largest precipitation deficit
| Region | County | Station | Altitude (m) | Anomaly (%) |
|---|---|---|---|---|
| Southwest | Clinton | Carlyle Rsvr | 153.0 | −99.4 |
| Southwest | Randolph | Chester | 119.0 | −88.3 |
| Southwest | Pulaski | Olmsted L&D | 114.0 | −85.9 |
| East Southeast | Jasper | Newton | 162.0 | −78.2 |
| Central | Woodford | Congerville 2NW | 195.0 | −77.9 |
| West Southwest | Macoupin | Medora 1 S | 185.0 | −77.7 |
| East Southeast | Coles | Charleston | 213.0 | −77.6 |
| East Southeast | Fayette | Vandalia | 149.0 | −75.3 |
| East Southeast | Coles | Mattoon Charleston Coles Co AP | 216.0 | −75.0 |
| East Southeast | Moultrie | Lovington | 208.0 | −72.6 |
Source: NOAA NCEI
Largest 24-hour rainfall at stations
| Station | County | Max 24 h rainfall (mm) | Date |
|---|---|---|---|
| Amboy Water | Lee | 127.3 | 2026-09-20 |
| Paw Paw 2S | Lee | 112.8 | 2026-09-20 |
| Yates City | Knox | 112.0 | 2026-09-16 |
| Elizabeth | Jo Daviess | 79.5 | 2026-09-19 |
| Chicago Aurora Muni AP | Kane | 79.0 | 2026-09-17 |
| Stockton 3NNE | Jo Daviess | 77.7 | 2026-09-19 |
| Earlville 3S | LaSalle | 77.2 | 2026-09-20 |
| Mt Carroll | Carroll | 75.4 | 2026-09-19 |
| Steward 3S | Lee | 75.2 | 2026-09-20 |
| Mendota 1S | LaSalle | 73.7 | 2026-09-20 |
Source: NOAA NCEI
Daily statewide mean precipitation
Source: NOAA NCEI
Daily statewide mean and grid-cell maximum
| Day | Statewide mean (mm) | Grid maximum (mm) | County |
|---|---|---|---|
| 2026-09-01 | 0.2 | 2.7 | Cook |
| 2026-09-02 | 0.0 | 1.2 | Lake |
| 2026-09-03 | 0.0 | 0.4 | Jo Daviess |
| 2026-09-04 | 0.2 | 6.4 | McHenry |
| 2026-09-05 | 0.1 | 4.9 | Lake |
| 2026-09-06 | 0.0 | 0.2 | Union |
| 2026-09-07 | 0.0 | 0.0 | Jo Daviess |
| 2026-09-08 | 0.0 | 0.6 | Gallatin |
| 2026-09-09 | 2.8 | 46.5 | Rock Island |
| 2026-09-10 | 7.1 | 33.9 | Clay |
| 2026-09-11 | 3.1 | 20.5 | Hardin |
| 2026-09-12 | 1.1 | 29.9 | Wabash |
| 2026-09-13 | 0.0 | 0.1 | Grundy |
| 2026-09-14 | 0.5 | 3.7 | Hancock |
| 2026-09-15 | 1.2 | 20.8 | Jo Daviess |
| 2026-09-16 | 13.6 | 48.9 | Knox |
| 2026-09-17 | 5.4 | 32.3 | Kane |
| 2026-09-18 | 1.9 | 16.3 | Cook |
| 2026-09-19 | 6.7 | 72.0 | Jo Daviess |
| 2026-09-20 | 16.7 | 100.7 | Lee |
| 2026-09-21 | 10.2 | 35.6 | Clay |
| 2026-09-22 | 1.0 | 8.8 | Jo Daviess |
| 2026-09-23 | 0.8 | 4.2 | Lee |
| 2026-09-24 | 0.0 | 0.3 | Christian |
| 2026-09-25 | 0.0 | 0.9 | Rock Island |
| 2026-09-26 | 0.1 | 3.5 | Rock Island |
| 2026-09-27 | 0.2 | 4.7 | Hancock |
| 2026-09-28 | 0.0 | 1.6 | Hancock |
| 2026-09-29 | 0.0 | 0.1 | Kane |
| 2026-09-30 | 3.6 | 24.6 | Jo Daviess |
Source: NOAA NCEI
Statewide precipitation in September of each year
Source: NOAA NCEI
Statewide accumulated precipitation was 76.8 mm, 90% of the 1991–2020 average (85.1 mm), category “Near normal”. It was the 26th driest September in the 1979–2026 series.
The region with the highest percentage of normal was Northwest (197%) and the lowest was Southwest (35%).
The largest daily grid-cell total was estimated on 20 September in Lee (100.7 mm).
Source: NOAA NCEI
4 Temperature
Source: NOAA NCEI
Mean temperature
Source: NOAA NCEI
Mean temperature anomaly (1991–2020)
Source: NOAA NCEI
Mean temperature anomaly by region
Source: NOAA NCEI
Stations with the largest positive anomaly
| Region | County | Station | Altitude (m) | Anomaly (°C) |
|---|---|---|---|---|
| West Southwest | Jersey | Jerseyville 2 SW | 186.0 | 5.0 |
| East Southeast | Clay | Flora | 147.0 | 4.7 |
| Southeast | Jefferson | Mt Vernon 3 NE | 149.0 | 4.6 |
| East Southeast | Marion | Salem | 168.0 | 4.6 |
| West Southwest | Morgan | Jacksonville 2E | 186.0 | 4.5 |
| West Southwest | Greene | White Hall 1 E | 177.0 | 4.5 |
| West Southwest | Montgomery | Hillsboro | 192.0 | 4.5 |
| East Southeast | Jasper | Newton | 162.0 | 4.4 |
| Southwest | St. Clair | Belleville Siu Rsch | 137.0 | 4.4 |
| Southwest | Jackson | Carbondale Sthrn Illinois AP | 122.0 | 4.4 |
Source: NOAA NCEI
Statewide mean temperature anomaly in September of each year
Source: NOAA NCEI
The statewide mean temperature was 22.8 °C, 3.5 °C above the 1991–2020 average (19.3 °C), category “Extremely above normal”. It was the warmest September in the 1979–2026 series.
By region, the largest anomaly was in Southwest (+4.3 °C) and the smallest in Northeast (+2.3 °C).
Source: NOAA NCEI
Source: NOAA NCEI
Maximum temperature anomaly (1991–2020)
Source: NOAA NCEI
Lowest and highest monthly mean maximum temperature by region
| Region | Lowest value (°C) | Station | Highest value (°C) | Station |
|---|---|---|---|---|
| Northwest | 24.7 | Illinois City Dam 16 | 28.6 | New Boston Dam 17 |
| Northeast | 23.2 | Chicago Waukegan Rgnl AP | 27.0 | Morris 1NW |
| West | 26.1 | Knoxville | 29.9 | Quincy Dam 21 |
| Central | 26.9 | General Wayne A Downing Intl A | 29.3 | Decatur AP |
| East | 27.1 | Hoopeston | 29.3 | Ogden |
| West Southwest | 29.3 | Springfield Abraham Lincoln Ca | 32.2 | Morrisonville |
| East Southeast | 29.1 | Tuscola | 32.4 | Flora |
| Southwest | 30.1 | Anna 4 N | 32.7 | Cairo 3N |
| Southeast | 31.2 | 1 ENE Fairfield | 31.9 | Mt Vernon 3 NE |
Station monthly means (GHCN-Daily, ≥ 80% of days with data).
Source: NOAA NCEI
Daily statewide maximum temperature
Source: NOAA NCEI
The statewide maximum temperature was 28.6 °C, 2.9 °C above the 1991–2020 average (25.7 °C), category “Extremely above normal”. It was the warmest September in the 1979–2026 series.
By region, the largest anomaly was in Southwest (+4.2 °C) and the smallest in Northwest (+1.4 °C).
Source: NOAA NCEI
Source: NOAA NCEI
Minimum temperature anomaly (1991–2020)
Source: NOAA NCEI
Lowest and highest monthly mean minimum temperature by region
| Region | Lowest value (°C) | Station | Highest value (°C) | Station |
|---|---|---|---|---|
| Northwest | 13.4 | Stockton 3NNE | 18.2 | Rock Is L&D 15 |
| Northeast | 13.6 | Shabbona 5 NNE | 18.2 | Chicago Northerly Is |
| West | 15.7 | Avon | 18.5 | Quincy Dam 21 |
| Central | 15.8 | Normal 4NE | 17.3 | General Wayne A Downing Intl A |
| East | 15.9 | Champaign 9 SW | 16.9 | Champaign 3S |
| West Southwest | 17.0 | Jacksonville 2E | 18.8 | Alton - Melvin Price L&D |
| East Southeast | 15.8 | Charleston | 18.6 | Newton |
| Southwest | 17.7 | Carbondale Sewage Plt | 20.5 | Olmsted L&D |
| Southeast | 16.9 | Mt Vernon 3 NE | 19.3 | Smithland L&D |
Station monthly means (GHCN-Daily, ≥ 80% of days with data).
Source: NOAA NCEI
Daily statewide minimum temperature
Source: NOAA NCEI
The statewide minimum temperature was 16.9 °C, 4.1 °C above the 1991–2020 average (12.8 °C), category “Extremely above normal”. It was the warmest September in the 1979–2026 series.
By region, the largest anomaly was in West Southwest (+4.5 °C) and the smallest in Northeast (+3.2 °C).
Source: NOAA NCEI
5 Climate extremes and records
Source: NOAA NCEI
Highest maximum temperature by county
| County | Station | Temperature (°C) | Date |
|---|---|---|---|
| Christian | Morrisonville | 40.6 | 2026-09-03 |
| Lawrence | Lawrenceville Vincennes Intl A | 40.0 | 2026-09-05 |
| Clark | Casey | 39.4 | 2026-09-03 |
| Clay | Flora | 39.4 | 2026-09-03 |
| Jackson | Carbondale Sthrn Illinois AP | 39.4 | 2026-09-05 |
| Jefferson | Mt Vernon 3 NE | 39.4 | 2026-09-05 |
| Wayne | 1 ENE Fairfield | 39.4 | 2026-09-06 |
| Adams | Quincy Dam 21 | 38.9 | 2026-09-04 |
| Perry | Du Quoin 4 SE | 38.9 | 2026-09-05 |
| Randolph | Kaskaskia Rvr Navigation Lock | 38.9 | 2026-09-06 |
| St. Clair | Cahokia St Louis Dwtn AP | 38.9 | 2026-09-05 |
| Crawford | Robinson | 38.3 | 2026-09-04 |
| Jersey | Jerseyville 2 SW | 38.3 | 2026-09-03 |
| Marion | Salem | 38.3 | 2026-09-02 |
| Alexander | Cairo 3N | 38.2 | 2026-09-05 |
| Champaign | Ogden | 37.8 | 2026-09-05 |
| Coles | Charleston | 37.8 | 2026-09-02 |
| Jasper | Newton | 37.8 | 2026-09-05 |
| Madison | Alton - Melvin Price L&D | 37.8 | 2026-09-06 |
| Morgan | Jacksonville 2E | 37.8 | 2026-09-02 |
The 20 most extreme of 63.
Source: NOAA NCEI
Lowest minimum temperature by county
| County | Station | Temperature (°C) | Date |
|---|---|---|---|
| DeKalb | Shabbona 5 NNE | 4.4 | 2026-09-28 |
| Coles | Charleston | 5.0 | 2026-09-29 |
| Champaign | Champaign 9 SW | 5.5 | 2026-09-28 |
| Jefferson | Mt Vernon 3 NE | 5.6 | 2026-09-28 |
| Logan | Lincoln | 5.6 | 2026-09-28 |
| McLean | Normal 4NE | 5.6 | 2026-09-30 |
| DuPage | Lisle - Morton Arboretum | 6.1 | 2026-09-27 |
| Kane | Chicago Aurora Muni AP | 6.1 | 2026-09-28 |
| Fulton | Avon | 6.7 | 2026-09-29 |
| Jo Daviess | Stockton 3NNE | 6.7 | 2026-09-14 |
| Lake | Chicago Waukegan Rgnl AP | 6.7 | 2026-09-27 |
| McHenry | Mchenry Stratton Lock/Dam | 6.7 | 2026-09-14 |
| Macon | Decatur AP | 6.7 | 2026-09-28 |
| Rock Island | Moline Quad City Intl AP | 6.7 | 2026-09-29 |
| Winnebago | Rockford Gtr Rockford AP | 6.7 | 2026-09-14 |
| LaSalle | Marseilles Lock/Dam | 7.2 | 2026-09-28 |
| Sangamon | Springfield Abraham Lincoln Ca | 7.2 | 2026-09-28 |
| Shelby | Windsor | 7.2 | 2026-09-28 |
| Stephenson | Freeport Wwtp | 7.2 | 2026-09-14 |
| Vermilion | Danville | 7.2 | 2026-09-26 |
The 20 most extreme of 61.
Source: NOAA NCEI
Station records broken
| Station | County | Variable | New value | Date | Previous record | Previous date |
|---|---|---|---|---|---|---|
| Casey | Clark | Highest maximum temperature | 39.4 | 2026-09-03 | 37.2 | 1899-09-05 |
| De Kalb | DeKalb | Highest maximum temperature | 35.0 | 2026-09-03 | 34.4 | 1978-09-08 |
| Earlville 3S | LaSalle | Highest 24 h rainfall | 77.2 | 2026-09-20 | 76.5 | 2019-09-28 |
| Flora | Clay | Highest maximum temperature | 39.4 | 2026-09-03 | 38.3 | 2011-09-02 |
| Fulton L&D #13 | Whiteside | Highest maximum temperature | 36.7 | 2026-09-03 | 35.6 | 1953-09-02 |
| Morrisonville | Christian | Highest maximum temperature | 40.6 | 2026-09-03 | 38.3 | 2011-09-02 |
| Salem | Marion | Highest maximum temperature | 38.3 | 2026-09-02 | 37.8 | 1960-09-06 |
| Shelbyville Dam | Shelby | Highest maximum temperature | 37.8 | 2026-09-03 | 36.7 | 2011-09-02 |
| Smithland L&D | Pope | Highest maximum temperature | 37.8 | 2026-09-05 | 37.2 | 1983-09-11 |
| Lawrenceville Vincennes Intl A | Lawrence | Highest maximum temperature | 40.0 | 2026-09-05 | 38.3 | 2011-09-03 |
| Carbondale Sthrn Illinois AP | Jackson | Highest maximum temperature | 39.4 | 2026-09-05 | 37.2 | 1999-09-04 |
Most extreme daily value of the period against the same period in all earlier years of record (at least 20 years; for weeks, the same calendar month).
Source: NOAA NCEI
Climate-extremes indices (statewide mean)
| Index | Description | Value | Normal | Difference | Unit |
|---|---|---|---|---|---|
| TX90p | Warm days (Tmax > 90th percentile) | 34.5 | 10.0 | 24.5 | % |
| TN90p | Warm nights (Tmin > 90th percentile) | 38.7 | 10.0 | 28.7 | % |
| TX10p | Cool days (Tmax < 10th percentile) | 0.8 | 10.0 | −9.2 | % |
| TN10p | Cold nights (Tmin < 10th percentile) | 0.0 | 10.0 | −10.0 | % |
| FD | Frost days (Tmin < 0 °C) | 0.0 | 0.0 | −0.0 | d |
| SU | Summer days (Tmax > 25 °C) | 20.9 | 17.7 | 3.2 | d |
| TR | Tropical nights (Tmin > 20 °C) | 9.6 | 1.8 | 7.9 | d |
| WSDI | Warm spell days (≥ 6 days) | 6.6 | — | — | d |
| CSDI | Cold spell days (≥ 6 days) | 0.0 | — | — | d |
| Rx1day | Maximum 1-day precipitation | 30.8 | 30.5 | 0.3 | mm |
| Rx5day | Maximum 5-day precipitation | 53.5 | 49.1 | 4.4 | mm |
| CDD | Consecutive dry days (< 1 mm) | 9.1 | 10.1 | −1.0 | d |
| CWD | Consecutive wet days (≥ 1 mm) | 4.6 | 3.0 | 1.6 | d |
Percentile indices relative to calendar-day percentiles of 1991–2020 (5-day window); counts and maxima averaged over the state's grid cells.
Source: NOAA NCEI
Heat and cold waves
| Dates | Type | Details |
|---|---|---|
| 2026-09-01 – 2026-09-06 | Heat wave | Up to 100% of the state above the 90th percentile of Tmax. Regions: Northwest, Northeast, West, Central, East, West Southwest, East Southeast, Southwest and Southeast. |
Wave: at least 3 consecutive days with at least half of the state above the 90th percentile of maximum temperature (heat) or below the 10th percentile of minimum temperature (cold). At most the 10 most intense are listed.
Source: NOAA NCEI
6 Drought
U.S. Drought Monitor, 29 September 2026
Source: National Drought Mitigation Center, USDA, NOAA
Share of the state by drought category, weekly U.S. Drought Monitor maps (%)
| Map of | None (%) | D0–D4 (%) | D1–D4 (%) | D2–D4 (%) | D3–D4 (%) | D4 (%) |
|---|---|---|---|---|---|---|
| 2026-09-01 | 94.4 | 5.6 | 0.0 | 0.0 | 0.0 | 0.0 |
| 2026-09-08 | 67.0 | 33.0 | 0.5 | 0.0 | 0.0 | 0.0 |
| 2026-09-15 | 55.0 | 45.0 | 0.5 | 0.0 | 0.0 | 0.0 |
| 2026-09-22 | 58.5 | 41.5 | 0.0 | 0.0 | 0.0 | 0.0 |
| 2026-09-29 | 64.8 | 35.2 | 9.6 | 0.0 | 0.0 | 0.0 |
Cumulative shares: D1–D4 is the share in moderate drought or worse.
Source: National Drought Mitigation Center, USDA, NOAA
Counties with the most severe drought, U.S. Drought Monitor of 29 September 2026 (% of the county)
| County | D0–D4 (%) | D1–D4 (%) | D2–D4 (%) | D3–D4 (%) | D4 (%) |
|---|---|---|---|---|---|
| Bond | 100.0 | 100.0 | 0.0 | 0.0 | 0.0 |
| Jersey | 100.0 | 100.0 | 0.0 | 0.0 | 0.0 |
| Clay | 100.0 | 99.1 | 0.0 | 0.0 | 0.0 |
| Richland | 100.0 | 98.5 | 0.0 | 0.0 | 0.0 |
| Calhoun | 100.0 | 86.0 | 0.0 | 0.0 | 0.0 |
| Greene | 100.0 | 77.3 | 0.0 | 0.0 | 0.0 |
| Madison | 100.0 | 69.6 | 0.0 | 0.0 | 0.0 |
| Lawrence | 100.0 | 68.0 | 0.0 | 0.0 | 0.0 |
| Marion | 100.0 | 67.5 | 0.0 | 0.0 | 0.0 |
| Fayette | 100.0 | 54.2 | 0.0 | 0.0 | 0.0 |
Cumulative shares: D1–D4 is the share in moderate drought or worse.
Source: National Drought Mitigation Center, USDA, NOAA
Standardized Precipitation Index (SPI) ending September 2026
Source: NOAA NCEI
Share of the state by SPI category
Source: NOAA NCEI
Counties with the lowest SPI-3
| County | SPI-1 | SPI-3 | SPI-6 | SPI-12 | Category |
|---|---|---|---|---|---|
| Clinton | −1.3 | −2.0 | −0.9 | −1.4 | Severe drought |
| Fayette | −0.9 | −1.8 | −0.5 | −0.9 | Severe drought |
| Bond | −1.2 | −1.6 | −0.5 | −1.0 | Severe drought |
| Marion | −0.7 | −1.4 | −0.2 | −0.9 | Moderate drought |
| Washington | −1.2 | −1.4 | −1.2 | −1.9 | Moderate drought |
| Jefferson | −0.8 | −1.2 | −1.2 | −2.4 | Moderate drought |
| Montgomery | −1.1 | −1.2 | 0.2 | −0.3 | Moderate drought |
| Christian | −0.8 | −1.0 | 0.1 | −0.3 | Moderate drought |
| Shelby | −0.9 | −1.0 | 0.3 | −0.2 | Moderate drought |
| Calhoun | −0.9 | −1.0 | −0.3 | −1.1 | Moderate drought |
Source: NOAA NCEI
U.S. Drought Monitor, map of 29 September 2026: 10% of the state in drought (D1–D4), 0% in severe drought or worse (D2–D4) and 0% in extreme or exceptional drought (D3–D4); 35% was abnormally dry or in drought (D0–D4).
On the map of 25 August 2026, 0% of the state was in drought: a change of +10 points over the period.
SPI-3 (Jul–Sep 2026): statewide mean +0.21; 11% of the state in drought (SPI ≤ −1.0) and 4% in severe or extreme drought.
Most affected counties: Clinton (−1.96), Fayette (−1.81) and Bond (−1.65).
SPI-1 (September 2026): 16% of the state in drought.
SPI-6 (Apr–Sep 2026): 6% of the state in drought.
SPI-12 (Oct 2025–Sep 2026): 19% of the state in drought.
7 Severe weather and notable events
The data for this section were not available when the report was issued (cyclone tracks and alerts).
9 Outlook
Outlook for October 2026: most likely tercile
Source: NOAA CPC
Outlook for Oct–Dec 2026: most likely tercile
Source: NOAA CPC
Probability of each tercile by region, Oct–Dec 2026 (%)
| Region | Precipitation: below | Precipitation: normal | Precipitation: above | Temp.: below | Temp.: normal | Temp.: above |
|---|---|---|---|---|---|---|
| Northwest | 32.0 | 30.0 | 38.0 | 26.0 | 33.0 | 41.0 |
| Northeast | 33.0 | 29.0 | 37.0 | 28.0 | 31.0 | 41.0 |
| West | 28.0 | 33.0 | 39.0 | 28.0 | 33.0 | 39.0 |
| Central | 30.0 | 30.0 | 40.0 | 30.0 | 31.0 | 39.0 |
| East | 33.0 | 31.0 | 36.0 | 30.0 | 32.0 | 38.0 |
| West Southwest | 26.0 | 35.0 | 40.0 | 28.0 | 34.0 | 38.0 |
| East Southeast | 30.0 | 33.0 | 37.0 | 28.0 | 34.0 | 38.0 |
| Southwest | 23.0 | 36.0 | 41.0 | 23.0 | 37.0 | 40.0 |
| Southeast | 28.0 | 34.0 | 39.0 | 23.0 | 36.0 | 41.0 |
Source: NOAA CPC
ENSO outlook: probability of each phase (%)
Source: NOAA CPC
Probabilistic outlook from the North American Multi-Model Ensemble (NMME), initialised in October 2026, relative to 1991–2020 terciles. It is not an official forecast: consult the National Weather Service and NOAA's Climate Prediction Center.
Precipitation, October 2026: above normal is favoured over 0% of the state and below normal over 27%.
Mean temperature, October 2026: above normal is favoured over 12% of the state and below normal over 0%.
Precipitation, Oct–Dec 2026: above normal is favoured over 35% of the state and below normal over 0%.
Mean temperature, Oct–Dec 2026: above normal is favoured over 28% of the state and below normal over 0%.
Probability of El Niño in the official ENSO outlook: SON 100%, OND 100%, NDJ 100% and DJF 100%.
10 Annexes
Report climate regions
Monthly precipitation by region (mm)
| Region | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep |
|---|---|---|---|---|---|---|---|---|---|
| Northwest | 18.9 | 5.2 | 79.0 | 179.9 | 35.7 | 188.1 | 66.5 | 152.1 | 182.2 |
| Northeast | 38.7 | 4.4 | 105.6 | 175.1 | 38.9 | 190.4 | 101.8 | 164.7 | 127.2 |
| West | 18.5 | 4.1 | 97.4 | 181.7 | 50.7 | 231.9 | 51.8 | 185.4 | 82.9 |
| Central | 28.4 | 6.6 | 119.3 | 158.9 | 51.8 | 216.4 | 52.2 | 183.9 | 67.7 |
| East | 24.9 | 7.4 | 116.5 | 149.6 | 50.0 | 204.4 | 74.9 | 218.5 | 65.9 |
| West Southwest | 23.8 | 18.6 | 134.6 | 163.0 | 91.8 | 173.6 | 74.0 | 79.0 | 35.1 |
| East Southeast | 27.8 | 29.5 | 157.6 | 145.9 | 137.0 | 195.4 | 71.4 | 93.9 | 38.7 |
| Southwest | 21.5 | 23.5 | 131.8 | 107.2 | 84.4 | 103.6 | 141.5 | 75.7 | 29.3 |
| Southeast | 23.6 | 16.6 | 130.1 | 88.2 | 92.6 | 119.7 | 113.1 | 75.5 | 39.7 |
Source: NOAA NCEI
Monthly maximum temperature by region (°C)
| Region | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep |
|---|---|---|---|---|---|---|---|---|---|
| Northwest | −2.2 | 6.0 | 12.7 | 18.9 | 23.3 | 26.6 | 29.9 | 27.2 | 25.6 |
| Northeast | −2.0 | 5.5 | 12.6 | 18.5 | 22.0 | 26.2 | 29.6 | 27.2 | 25.6 |
| West | 0.0 | 8.3 | 15.6 | 20.8 | 23.5 | 27.3 | 30.6 | 28.6 | 27.7 |
| Central | 0.0 | 7.2 | 15.8 | 20.9 | 23.4 | 27.3 | 30.1 | 28.6 | 28.1 |
| East | −0.5 | 6.1 | 15.4 | 20.5 | 22.8 | 27.2 | 29.8 | 28.1 | 28.0 |
| West Southwest | 1.9 | 8.7 | 17.8 | 22.4 | 23.7 | 28.5 | 31.1 | 30.1 | 30.3 |
| East Southeast | 1.9 | 7.4 | 17.4 | 22.2 | 22.8 | 28.1 | 30.4 | 29.7 | 30.5 |
| Southwest | 4.1 | 9.7 | 19.5 | 23.8 | 23.9 | 29.1 | 31.4 | 30.7 | 31.4 |
| Southeast | 3.8 | 8.7 | 19.0 | 23.8 | 23.5 | 28.8 | 31.2 | 30.9 | 31.2 |
Source: NOAA NCEI
Monthly mean temperature by region (°C)
| Region | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep |
|---|---|---|---|---|---|---|---|---|---|
| Northwest | −6.7 | −0.3 | 6.1 | 12.6 | 16.1 | 21.0 | 24.2 | 22.1 | 20.5 |
| Northeast | −6.3 | −0.2 | 6.2 | 12.2 | 15.3 | 20.6 | 24.0 | 22.3 | 20.5 |
| West | −4.9 | 1.9 | 8.5 | 14.2 | 17.0 | 22.0 | 25.1 | 23.4 | 22.4 |
| Central | −4.9 | 1.0 | 8.7 | 14.4 | 16.8 | 21.8 | 24.4 | 23.3 | 22.3 |
| East | −5.3 | 0.3 | 8.4 | 14.0 | 16.2 | 21.5 | 24.2 | 22.7 | 22.0 |
| West Southwest | −3.4 | 2.4 | 10.2 | 15.8 | 17.5 | 22.9 | 25.4 | 24.3 | 24.0 |
| East Southeast | −3.1 | 1.8 | 10.4 | 16.1 | 17.1 | 22.7 | 25.1 | 24.1 | 24.0 |
| Southwest | −1.3 | 3.6 | 12.3 | 17.6 | 18.4 | 23.8 | 26.2 | 25.2 | 25.0 |
| Southeast | −1.2 | 3.2 | 12.5 | 17.6 | 18.2 | 23.5 | 26.1 | 25.2 | 25.0 |
Source: NOAA NCEI
Monthly minimum temperature by region (°C)
| Region | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep |
|---|---|---|---|---|---|---|---|---|---|
| Northwest | −11.3 | −6.5 | −0.5 | 6.4 | 9.0 | 15.4 | 18.5 | 17.1 | 15.3 |
| Northeast | −10.7 | −5.9 | −0.2 | 5.9 | 8.5 | 15.0 | 18.3 | 17.3 | 15.3 |
| West | −9.9 | −4.5 | 1.4 | 7.7 | 10.5 | 16.7 | 19.6 | 18.2 | 17.1 |
| Central | −9.7 | −5.2 | 1.5 | 8.0 | 10.2 | 16.3 | 18.7 | 17.9 | 16.5 |
| East | −10.2 | −5.6 | 1.3 | 7.5 | 9.6 | 15.8 | 18.5 | 17.3 | 15.9 |
| West Southwest | −8.8 | −3.9 | 2.5 | 9.2 | 11.4 | 17.3 | 19.6 | 18.5 | 17.8 |
| East Southeast | −8.2 | −3.8 | 3.5 | 10.0 | 11.3 | 17.4 | 19.8 | 18.6 | 17.5 |
| Southwest | −6.6 | −2.4 | 5.2 | 11.4 | 13.0 | 18.4 | 21.1 | 19.6 | 18.6 |
| Southeast | −6.2 | −2.4 | 6.0 | 11.5 | 12.9 | 18.1 | 20.9 | 19.6 | 18.7 |
Source: NOAA NCEI
Stations used
| Id | Name | County | Latitude | Longitude | Altitude (m) | Days with data (Tmax) (%) |
|---|---|---|---|---|---|---|
| USC00110072 | Aledo | Mercer | 41.2 | −90.7 | 223.7 | 97.0 |
| USC00110137 | Alton - Melvin Price L&D | Madison | 38.9 | −90.1 | 123.4 | 93.0 |
| USC00110146 | Amboy Water | Lee | 41.7 | −89.3 | 230.1 | 0.0 |
| USC00110187 | Anna 4 N | Union | 37.5 | −89.2 | 180.7 | 100.0 |
| USC00110251 | Arthur 1W | Moultrie | 39.7 | −88.5 | 204.2 | 0.0 |
| USC00110306 | Athens 4SW | Menard | 39.9 | −89.8 | 181.1 | 0.0 |
| USC00110330 | Augusta | Hancock | 40.2 | −90.9 | 203.6 | 0.0 |
| USC00110338 | Aurora Water | Kane | 41.8 | −88.3 | 205.7 | 97.0 |
| USC00110356 | Avon | Fulton | 40.7 | −90.4 | 195.1 | 97.0 |
| USC00110442 | Barrington 3SW | Cook | 42.1 | −88.2 | 269.1 | 100.0 |
| USC00110500 | Beecher City | Effingham | 39.2 | −88.8 | 185.3 | 0.0 |
| USC00110598 | Bentley | Hancock | 40.3 | −91.1 | 198.1 | 97.0 |
| USC00110761 | Bloomington Wtr Wks | McLean | 40.5 | −89.0 | 233.5 | 0.0 |
| USC00110803 | Bourbonnais 3NW | Kankakee | 41.2 | −87.9 | 200.6 | 0.0 |
| USC00111083 | Buffalo 3NNE | Sangamon | 39.9 | −89.4 | 187.1 | 0.0 |
| USC00111250 | Canton | Fulton | 40.5 | −90.0 | 195.1 | 0.0 |
| USC00111265 | Carbondale Sewage Plt | Jackson | 37.7 | −89.2 | 118.9 | 100.0 |
| USC00111290 | Carlyle Rsvr | Clinton | 38.6 | −89.4 | 152.7 | 33.0 |
| USC00111329 | Casey | Clark | 39.3 | −88.0 | 189.0 | 80.0 |
| USC00111386 | Centralia | Marion | 38.6 | −89.1 | 147.8 | 0.0 |
| USC00111436 | Charleston | Coles | 39.5 | −88.2 | 213.4 | 97.0 |
| USC00111491 | Chester | Randolph | 37.9 | −89.8 | 118.9 | 0.0 |
| USC00111550 | Chicago Northerly Is | Cook | 41.9 | −87.6 | 177.7 | 97.0 |
| USC00111577 | Chicago Midway AP 3SW | Cook | 41.7 | −87.8 | 189.0 | 100.0 |
| USC00111655 | Cisco | Piatt | 40.0 | −88.7 | 209.7 | 0.0 |
| USC00111664 | Cisne 2 S | Wayne | 38.5 | −88.4 | 138.4 | 0.0 |
| USC00111700 | Clay City 6SSE | Clay | 38.6 | −88.3 | 140.2 | 0.0 |
| USC00111743 | Clinton 1SSW | De Witt | 40.1 | −89.0 | 211.8 | 0.0 |
| USC00111836 | Congerville 2NW | Woodford | 40.6 | −89.2 | 195.1 | 20.0 |
| USC00112048 | Crystal Lake 4NW | McHenry | 42.3 | −88.4 | 283.8 | 0.0 |
| USC00112140 | Danville | Vermilion | 40.1 | −87.6 | 169.2 | 100.0 |
| USC00112145 | Danville Sewage Plt | Vermilion | 40.1 | −87.6 | 163.4 | 0.0 |
| USC00112193 | Decatur Wtp | Macon | 39.8 | −89.0 | 194.8 | 0.0 |
| USC00112223 | De Kalb | DeKalb | 41.9 | −88.8 | 267.6 | 93.0 |
| USC00112348 | Dixon Wwtp | Lee | 41.8 | −89.5 | 198.1 | 27.0 |
| USC00112353 | Dixon Springs Agric Ctr | Pope | 37.4 | −88.7 | 160.6 | 0.0 |
| USC00112483 | Du Quoin 4 SE | Perry | 38.0 | −89.2 | 128.0 | 30.0 |
| USC00112500 | Dwight Wwtp | Livingston | 41.1 | −88.4 | 190.5 | 53.0 |
| USC00112510 | Earlville 3S | LaSalle | 41.6 | −88.9 | 210.9 | 0.0 |
| USC00112679 | Edwardsville 2 W | Madison | 38.8 | −90.0 | 141.7 | 0.0 |
| USC00112685 | Effingham SE | Effingham | 39.1 | −88.5 | 161.8 | 0.0 |
| USC00112736 | Elgin Water | Kane | 42.1 | −88.3 | 227.1 | 97.0 |
| USC00112745 | Elizabeth | Jo Daviess | 42.3 | −90.2 | 205.7 | 97.0 |
| USC00112923 | Fairbury Wwtp | Livingston | 40.8 | −88.5 | 204.2 | 0.0 |
| USC00112931 | 1 ENE Fairfield | Wayne | 38.4 | −88.4 | 140.8 | 100.0 |
| USC00113061 | Fisher | Champaign | 40.3 | −88.3 | 219.8 | 0.0 |
| USC00113106 | Flora | Clay | 38.7 | −88.5 | 146.6 | 93.0 |
| USC00113107 | Flora 2 | Clay | 38.7 | −88.5 | 149.0 | 0.0 |
| USC00113120 | Ft Massac Sp | Massac | 37.1 | −88.7 | 104.2 | 0.0 |
| USC00113262 | Freeport Wwtp | Stephenson | 42.3 | −89.6 | 228.6 | 100.0 |
| USC00113290 | Fulton L&D #13 | Whiteside | 41.9 | −90.2 | 180.4 | 100.0 |
| USC00113320 | Galesburg | Knox | 40.9 | −90.4 | 232.0 | 97.0 |
| USC00113384 | Geneseo | Henry | 41.5 | −90.1 | 194.8 | 97.0 |
| USC00113395 | Germantown Hills | Woodford | 40.8 | −89.5 | 238.7 | 0.0 |
| USC00113455 | Gladstone L/D 18 | Henderson | 40.9 | −91.0 | 164.0 | 87.0 |
| USC00113490 | Glen Ellyn 4S | DuPage | 41.8 | −88.1 | 207.3 | 0.0 |
| USC00113580 | Olmsted L&D | Pulaski | 37.2 | −89.1 | 114.3 | 93.0 |
| USC00113879 | Harrisburg | Saline | 37.7 | −88.5 | 111.3 | 0.0 |
| USC00113902 | Harvard Wwtp | McHenry | 42.4 | −88.6 | 279.2 | 0.0 |
| USC00114012 | Hennepin | Putnam | 41.3 | −89.3 | 157.0 | 100.0 |
| USC00114089 | Highland | Madison | 38.7 | −89.7 | 158.5 | 0.0 |
| USC00114108 | Hillsboro | Montgomery | 39.2 | −89.5 | 192.0 | 90.0 |
| USC00114198 | Hoopeston | Vermilion | 40.5 | −87.7 | 216.4 | 100.0 |
| USC00114317 | Hutsonville | Crawford | 39.1 | −87.7 | 147.2 | 0.0 |
| USC00114355 | Illinois City Dam 16 | Rock Island | 41.4 | −91.0 | 167.6 | 100.0 |
| USC00114442 | Jacksonville 2E | Morgan | 39.7 | −90.2 | 185.9 | 100.0 |
| USC00114489 | Jerseyville 2 SW | Jersey | 39.1 | −90.3 | 185.9 | 100.0 |
| USC00114530 | Joliet Brandon Road Lock/Dam | Will | 41.5 | −88.1 | 165.5 | 100.0 |
| USC00114603 | Kankakee Wwtp | Kankakee | 41.1 | −87.9 | 182.9 | 97.0 |
| USC00114629 | Kaskaskia Rvr Navigation Lock | Randolph | 38.0 | −89.9 | 118.9 | 93.0 |
| USC00114710 | Kewanee 1E | Henry | 41.2 | −89.9 | 237.7 | 100.0 |
| USC00114780 | Knoxville | Knox | 40.9 | −90.3 | 221.9 | 100.0 |
| USC00114805 | Lacon | Marshall | 41.0 | −89.4 | 139.6 | 0.0 |
| USC00114823 | La Harpe | Hancock | 40.6 | −91.0 | 206.7 | 100.0 |
| USC00114833 | Lake Springfield | Sangamon | 39.8 | −89.6 | 177.1 | 0.0 |
| USC00114890 | Lansing 2S | Cook | 41.5 | −87.5 | 187.1 | 0.0 |
| USC00114957 | Lawrenceville 2WSW | Lawrence | 38.7 | −87.7 | 137.5 | 100.0 |
| USC00115079 | Lincoln | Logan | 40.2 | −89.3 | 177.7 | 100.0 |
| USC00115097 | Lisle - Morton Arboretum | DuPage | 41.8 | −88.1 | 206.3 | 100.0 |
| USC00115110 | Little Red School House | Cook | 41.7 | −87.9 | 219.2 | 0.0 |
| USC00115219 | Lovington | Moultrie | 39.7 | −88.6 | 207.9 | 0.0 |
| USC00115272 | Mackinaw 3WSW | Tazewell | 40.5 | −89.4 | 201.8 | 0.0 |
| USC00115280 | Macomb | McDonough | 40.5 | −90.7 | 185.9 | 0.0 |
| USC00115314 | Manhattan 5ENE | Will | 41.5 | −87.9 | 228.0 | 0.0 |
| USC00115372 | Marseilles Lock/Dam | LaSalle | 41.3 | −88.8 | 148.4 | 87.0 |
| USC00115430 | Mattoon | Coles | 39.5 | −88.4 | 213.4 | 0.0 |
| USC00115493 | Mchenry Stratton Lock/Dam | McHenry | 42.3 | −88.3 | 224.3 | 100.0 |
| USC00115539 | Medora 1 S | Macoupin | 39.2 | −90.1 | 185.0 | 0.0 |
| USC00115562 | Mendota 1S | LaSalle | 41.5 | −89.1 | 218.8 | 0.0 |
| USC00115660 | Milstadt 2SW | St. Clair | 38.4 | −90.1 | 198.1 | 0.0 |
| USC00115712 | Minonk | Woodford | 40.9 | −89.0 | 228.6 | 90.0 |
| USC00115763 | Monee | Will | 41.4 | −87.8 | 242.9 | 0.0 |
| USC00115768 | Monmouth | Warren | 40.9 | −90.6 | 219.5 | 0.0 |
| USC00115772 | Monmouth 4NW | Warren | 40.9 | −90.7 | 220.7 | 90.0 |
| USC00115825 | Morris 1NW | Grundy | 41.4 | −88.4 | 159.7 | 100.0 |
| USC00115833 | Morrison | Whiteside | 41.8 | −90.0 | 192.6 | 0.0 |
| USC00115841 | Morrisonville | Christian | 39.4 | −89.5 | 192.0 | 93.0 |
| USC00115876 | Morton | Tazewell | 40.6 | −89.5 | 213.7 | 0.0 |
| USC00115901 | Mt Carroll | Carroll | 42.1 | −90.0 | 215.8 | 93.0 |
| USC00115917 | Mt Olive 1 E | Macoupin | 39.1 | −89.7 | 204.2 | 0.0 |
| USC00115927 | Mt Pulaski | Logan | 40.0 | −89.3 | 201.5 | 0.0 |
| USC00115943 | Mt Vernon 3 NE | Jefferson | 38.4 | −88.9 | 149.4 | 100.0 |
| USC00115950 | Moweaqua 2S | Shelby | 39.6 | −89.0 | 190.5 | 0.0 |
| USC00115983 | Murphysboro 2 SW | Jackson | 37.8 | −89.4 | 167.6 | 0.0 |
| USC00116024 | Neoga | Cumberland | 39.3 | −88.5 | 195.7 | 0.0 |
| USC00116080 | New Boston Dam 17 | Mercer | 41.2 | −91.1 | 166.7 | 83.0 |
| USC00116157 | Newton | Jasper | 39.0 | −88.2 | 161.8 | 97.0 |
| USC00116200 | Normal 4NE | McLean | 40.5 | −88.9 | 240.8 | 100.0 |
| USC00116344 | Ogden | Champaign | 40.1 | −88.0 | 205.7 | 100.0 |
| USC00116490 | Oregon | Ogle | 42.0 | −89.3 | 206.7 | 0.0 |
| USC00116526 | Ottawa 4SW | LaSalle | 41.3 | −88.9 | 166.1 | 93.0 |
| USC00116579 | Pana | Christian | 39.4 | −89.1 | 198.1 | 100.0 |
| USC00116610 | Paris Stp | Edgar | 39.6 | −87.7 | 197.8 | 100.0 |
| USC00116616 | Park Forest Water | Cook | 41.5 | −87.7 | 216.4 | 93.0 |
| USC00116661 | Paw Paw 2S | Lee | 41.7 | −89.0 | 271.0 | 90.0 |
| USC00116710 | Peoria 5NW | Peoria | 40.7 | −89.6 | 213.4 | 0.0 |
| USC00116725 | Peotone | Will | 41.3 | −87.8 | 218.8 | 0.0 |
| USC00116738 | Perry 6 NW | Pike | 39.8 | −90.8 | 198.1 | 0.0 |
| USC00116765 | Petersburg 1E | Menard | 40.0 | −89.8 | 182.9 | 20.0 |
| USC00116769 | Philo | Champaign | 40.0 | −88.2 | 219.5 | 0.0 |
| USC00117077 | Quincy Dam 21 | Adams | 39.9 | −91.4 | 147.2 | 97.0 |
| USC00117157 | Red Bud 2 S | Randolph | 38.2 | −90.0 | 128.0 | 0.0 |
| USC00117329 | Roanoke | Woodford | 40.8 | −89.2 | 219.5 | 0.0 |
| USC00117345 | Robinson | Crawford | 39.0 | −87.8 | 163.1 | 100.0 |
| USC00117391 | Rock Is L&D 15 | Rock Island | 41.5 | −90.6 | 173.1 | 100.0 |
| USC00117457 | Romeoville Wfo | Will | 41.6 | −88.1 | 201.2 | 100.0 |
| USC00117636 | Salem | Marion | 38.6 | −88.9 | 167.6 | 97.0 |
| USC00117833 | Shabbona 3S | DeKalb | 41.7 | −88.9 | 259.1 | 0.0 |
| USC00117860 | Shawneetown 3 WSW | Gallatin | 37.7 | −88.2 | 121.9 | 0.0 |
| USC00117876 | Shelbyville Dam | Shelby | 39.4 | −88.8 | 198.1 | 100.0 |
| USC00117896 | Sherman | Sangamon | 39.9 | −89.6 | 177.1 | 0.0 |
| USC00117952 | Sidell 4N | Vermilion | 40.0 | −87.8 | 204.8 | 97.0 |
| USC00118020 | Smithland L&D | Pope | 37.2 | −88.4 | 108.8 | 100.0 |
| USC00118210 | St Libory | St. Clair | 38.4 | −89.7 | 129.5 | 0.0 |
| USC00118254 | Steward 3S | Lee | 41.8 | −89.0 | 246.9 | 0.0 |
| USC00118293 | Stockton 3NNE | Jo Daviess | 42.4 | −90.0 | 295.7 | 100.0 |
| USC00118353 | Streator 2SE | Livingston | 41.1 | −88.8 | 184.7 | 0.0 |
| USC00118491 | Taylorville 2SE | Christian | 39.5 | −89.3 | 188.1 | 0.0 |
| USC00118684 | Tuscola | Douglas | 39.8 | −88.3 | 198.4 | 100.0 |
| USC00118740 | Champaign 3S | Champaign | 40.1 | −88.2 | 220.1 | 100.0 |
| USC00118781 | Vandalia | Fayette | 39.0 | −89.1 | 149.4 | 0.0 |
| USC00118916 | Walnut | Bureau | 41.6 | −89.6 | 213.4 | 0.0 |
| USC00118932 | Waltonville | Jefferson | 38.2 | −89.1 | 155.8 | 0.0 |
| USC00119002 | Waterloo 6SW | Monroe | 38.3 | −90.2 | 222.5 | 0.0 |
| USC00119021 | Watseka Public Works | Iroquois | 40.8 | −87.7 | 191.1 | 0.0 |
| USC00119148 | W Frankfort | Franklin | 37.9 | −88.9 | 131.1 | 0.0 |
| USC00119241 | White Hall 1 E | Greene | 39.4 | −90.4 | 176.8 | 97.0 |
| USC00119275 | Willisville | Randolph | 38.0 | −89.6 | 151.2 | 0.0 |
| USC00119354 | Windsor | Shelby | 39.4 | −88.6 | 210.3 | 100.0 |
| USC00119480 | Woodstock 5NW | McHenry | 42.4 | −88.5 | 288.6 | 0.0 |
| USC00119816 | Yates City | Knox | 40.8 | −90.0 | 203.9 | 0.0 |
| USW00003887 | Decatur AP | Macon | 39.8 | −88.9 | 205.1 | 100.0 |
| USW00003960 | Cahokia St Louis Dwtn AP | St. Clair | 38.6 | −90.1 | 123.4 | 100.0 |
| USW00004808 | Chicago Aurora Muni AP | Kane | 41.8 | −88.5 | 213.7 | 100.0 |
| USW00004838 | Chicago Palwaukee AP | Cook | 42.1 | −87.9 | 191.7 | 100.0 |
| USW00013802 | Belleville Siu Rsch | St. Clair | 38.5 | −89.8 | 137.2 | 100.0 |
| USW00013809 | Lawrenceville Vincennes Intl A | Lawrence | 38.8 | −87.6 | 130.1 | 100.0 |
| USW00014819 | Chicago Midway AP | Cook | 41.8 | −87.8 | 185.9 | 100.0 |
| USW00014834 | Joliet | Will | 41.5 | −88.1 | 167.9 | 0.0 |
| USW00014842 | General Wayne A Downing Intl A | Peoria | 40.7 | −89.7 | 199.6 | 100.0 |
| USW00014880 | Chicago Waukegan Rgnl AP | Lake | 42.4 | −87.9 | 216.4 | 100.0 |
| USW00014923 | Moline Quad City Intl AP | Rock Island | 41.4 | −90.5 | 175.6 | 100.0 |
| USW00053802 | Mattoon Charleston Coles Co AP | Coles | 39.5 | −88.3 | 216.4 | 100.0 |
| USW00054808 | Champaign 9 SW | Champaign | 40.1 | −88.4 | 213.4 | 100.0 |
| USW00054811 | Shabbona 5 NNE | DeKalb | 41.8 | −88.9 | 262.4 | 100.0 |
| USW00054831 | Bloomington Normal AP | McLean | 40.5 | −89.0 | 263.7 | 100.0 |
| USW00093809 | Cairo 3N | Alexander | 37.0 | −89.2 | 95.4 | 100.0 |
| USW00093810 | Carbondale Sthrn Illinois AP | Jackson | 37.8 | −89.2 | 121.9 | 100.0 |
| USW00093822 | Springfield Abraham Lincoln Ca | Sangamon | 39.8 | −89.7 | 179.8 | 100.0 |
| USW00093989 | Quincy Rgnl AP | Adams | 39.9 | −91.2 | 231.6 | 100.0 |
| USW00094822 | Rockford Gtr Rockford AP | Winnebago | 42.2 | −89.1 | 221.0 | 100.0 |
| USW00094846 | Chicago Ohare Intl AP | DuPage | 42.0 | −87.9 | 204.8 | 100.0 |
| USW00094870 | Champaign Urbana Willard AP | Champaign | 40.0 | −88.3 | 226.5 | 100.0 |
| USW00094892 | Chicago W Chicago Dupage AP | DuPage | 41.9 | −88.3 | 228.3 | 100.0 |
Source: NOAA NCEI
11 Glossary, methodology and sources
Anomaly: difference between the observed value and its 1991–2020 normal. Percent of normal: observed total divided by the normal, times 100. Station record: most extreme daily value for the same month in all earlier years of record (at least 20 years).
Temperature: NOAA nClimGrid-Daily. Precipitation: NOAA nClimGrid-Daily. nClimGrid-Daily is the grid behind NOAA's official statewide values; it is averaged here from 1/24° to 1/8° (about 12 km). Mean temperature is (Tmax + Tmin)/2. Statewide, regional and county averages are weighted by the area of each grid cell inside each polygon. Temperature maps, frost days and annex tables are given by region; regions are NOAA NCEI climate divisions, with each county in the division of its centroid. Recent weeks use NCEI's preliminary file of the month; such reports are marked preliminary and updated when the final file is published. Normals refer to 1991-2020; ranks compare values rounded to one decimal. Stations: GHCN-Daily (NOAA NCEI) cooperative and first-order stations; values flagged by its quality control are discarded, as are daily values more than 5 robust standard deviations from the station median and variables whose monthly anomaly differs by more than 3 °C from the gridded analysis. Period means require at least 80% of days with data and station normals at least 20 complete years. This report is generated automatically and does not replace official information from the National Weather Service or the state climatologist.
| Source | Product | License | Citation |
|---|---|---|---|
| NOAA CPC | Official ENSO probabilities | Public domain (NOAA) | — |
| NOAA CPC | ONI, Niño-region SST indices (OISST v2.1), NAO and AO | Public domain (NOAA) | NOAA Climate Prediction Center climate indices. |
| NOAA NCEI / PSL | Extended Reconstructed SST v5 (ERSST v5), 2° | Public domain (NOAA) | Huang et al. (2017), J. Climate, doi:10.1175/JCLI-D-16-0836.1 |
| GDACS | Global Disaster Alert and Coordination System event list | See provider terms | — |
| NOAA NCEI | GHCN-Daily | Public domain (NOAA) | Menne et al. (2012), J. Atmos. Oceanic Technol., doi:10.1175/JTECH-D-11-00103.1 |
| NOAA NCEI | Pacific Decadal Oscillation index (ERSST v5) | Public domain (NOAA) | — |
| NOAA NCEI | nClimGrid-Daily, contiguous United States (1/24°, averaged here to 1/8°) | Public domain (NOAA) | Durre, I., et al. (2022). NOAA's nClimGrid-Daily Version 1. NOAA National Centers for Environmental Information. doi:10.25921/c4gt-r169 |
| NOAA CPC | North American Multi-Model Ensemble (NMME) tercile probabilities, 1° | Public domain (NOAA) | Kirtman et al. (2014), Bull. Amer. Meteor. Soc., doi:10.1175/BAMS-D-12-00050.1 |
| NOAA PSL | Real-time OLR MJO Index (ROMI) | Public domain (NOAA) | Kiladis et al. (2014), Mon. Wea. Rev., doi:10.1175/MWR-D-13-00301.1 |
| National Drought Mitigation Center, USDA, NOAA | U.S. Drought Monitor, weekly maps and area statistics | Free to use with credit (NDMC) | The U.S. Drought Monitor is jointly produced by the National Drought Mitigation Center at the University of Nebraska-Lincoln, the United States Department of Agriculture and the National Oceanic and Atmospheric Administration. Map courtesy of NDMC. |
| US Census Bureau TIGERweb | US Census Bureau, TIGERweb counties (generalised) | Public domain (US Government work) | — |
Generated by ClimaBulletin (climabulletin.org), open source. Questions and comments: [email protected].