Illinois weather in August: Statewide normals and every place, NOAA 1991-2020
In August, Illinois's statewide normal high is 84°F and normal low 63°F; normal highs run from 79°F in Barrington to 89°F in Anna (NOAA 1991-2020 normals).
- Statewide normal high
- 84°FAugust, 1991-2020
- Statewide normal low
- 63°FAugust, 1991-2020
- Statewide normal precipitation
- 3.56 inAugust
- Warmest place
- 89°Fnormal high, Anna
- Coolest place
- 79°Fnormal high, Barrington
Where is Illinois warmest and wettest in August?
Anna has the warmest August afternoons (89°F) and Barrington the coolest (79°F). Barrington gets the most precipitation (4.58 in) and Mattoon the least (2.42 in).
Statewide, August averaged 75.5°F in 2021, 73.6°F in 2022, 73.5°F in 2023, 73.7°F in 2024, 73.0°F in 2025, 74.4°F in 2026, against a 1991-2020 normal of 73.6°F.
| Place | High | Low | Precip. | Snow |
|---|---|---|---|---|
| Chicago | 83°F | 65°F | 4.25 | 0.0 |
| Aurora | 82°F | 63°F | 3.86 | 0.0 |
| Joliet | 82°F | 63°F | 3.97 | 0.0 |
| Rockford | 82°F | 62°F | 4.19 | 0.0 |
| Elgin | 82°F | 61°F | 4.33 | 0.0 |
| Springfield | 85°F | 64°F | 3.37 | 0.0 |
| Peoria | 85°F | 64°F | 3.31 | 0.0 |
| Champaign | 84°F | 62°F | 3.12 | – |
| Waukegan | 80°F | 62°F | – | – |
| Bloomington | 83°F | 61°F | 4.13 | – |
| Decatur | 84°F | 63°F | 3.03 | – |
| Wheaton | 84°F | 62°F | 4.40 | 0.0 |
| Normal | 84°F | 61°F | 3.83 | 0.0 |
| Moline | 84°F | 63°F | 3.97 | 0.0 |
| Crystal Lake | 82°F | 61°F | 3.81 | 0.0 |
| Romeoville | 83°F | 63°F | 4.36 | 0.0 |
| Belleville | 89°F | 65°F | 3.92 | 0.0 |
| DeKalb | 81°F | 61°F | 4.06 | 0.0 |
| Quincy | 85°F | 65°F | 3.93 | – |
| Streamwood | 85°F | 60°F | 4.45 | 0.0 |
| Wheeling | 82°F | 65°F | 3.70 | – |
| Rock Island | 82°F | 63°F | 4.03 | – |
| Mundelein | 81°F | 61°F | 4.19 | 0.0 |
| Galesburg | 82°F | 63°F | 3.89 | 0.0 |
| Burbank | 83°F | 67°F | 4.10 | 0.0 |
| Danville | 84°F | 63°F | 3.31 | – |
| West Chicago | 82°F | 62°F | 3.84 | – |
| Alton | 86°F | 67°F | 3.30 | – |
| Lisle | 83°F | 60°F | 4.35 | – |
| Kankakee | 83°F | 63°F | 3.85 | 0.0 |
| Freeport | 81°F | 60°F | 4.21 | 0.0 |
| Carbondale | 87°F | 65°F | 3.05 | – |
| Park Forest | 82°F | 62°F | 4.02 | 0.0 |
| Ottawa | 82°F | 62°F | 3.72 | 0.0 |
| Jacksonville | 86°F | 63°F | 3.32 | – |
| Charleston | 87°F | 64°F | 2.94 | 0.0 |
| Cahokia Heights | 88°F | 66°F | 3.68 | – |
| Mattoon | 84°F | 64°F | 2.42 | – |
| Dixon | 81°F | 62°F | 4.19 | 0.0 |
| Antioch | 81°F | 63°F | – | – |
| Morris | 83°F | 63°F | 4.01 | 0.0 |
| Channahon | 83°F | 63°F | 3.75 | 0.0 |
| Mount Vernon | 85°F | 65°F | 3.33 | 0.0 |
| Lincoln | 84°F | 61°F | 3.47 | 0.0 |
| Effingham | 87°F | 64°F | 3.19 | 0.0 |
| Streator | 84°F | 64°F | 3.70 | 0.0 |
| Rantoul | 86°F | 62°F | 3.86 | – |
| Kewanee | 82°F | 61°F | 3.86 | 0.0 |
| Pontiac | 83°F | 64°F | 3.73 | 0.0 |
| Barrington | 79°F | 61°F | 4.58 | 0.0 |
| Peru | 82°F | 61°F | 3.70 | 0.0 |
| Rochelle | 81°F | 60°F | 3.92 | – |
| Lake Villa | 81°F | 62°F | 3.27 | 0.0 |
| Monmouth | 83°F | 62°F | 3.92 | 0.0 |
| Olney | 86°F | 64°F | 3.19 | 0.0 |
| Jerseyville | 85°F | 63°F | 3.72 | 0.0 |
| Paris | 83°F | 62°F | 3.57 | 0.0 |
| Harrisburg | 88°F | 66°F | 3.58 | – |
| Marengo | 82°F | 60°F | 4.22 | 0.0 |
| Princeton | 82°F | 61°F | 4.02 | 0.0 |
| Vandalia | 86°F | 64°F | 3.24 | – |
| Robinson | 86°F | 63°F | 3.45 | – |
| Salem | 87°F | 65°F | 3.80 | 0.0 |
| Mount Carmel | 86°F | 67°F | 3.24 | 0.0 |
| Benton | 87°F | 66°F | – | – |
| Geneseo | 83°F | 63°F | 4.10 | 0.0 |
| Hillsboro | 87°F | 65°F | 3.14 | – |
| Du Quoin | 86°F | 65°F | 3.30 | 0.0 |
| Carlinville | 85°F | 64°F | 3.24 | 0.0 |
| Pana | 86°F | 63°F | 3.00 | 0.0 |
| Fairfield | 89°F | 66°F | 3.51 | – |
| Marseilles | 82°F | 61°F | 4.09 | 0.0 |
| Hoopeston | 83°F | 63°F | 3.96 | 0.0 |
| Carmi | 87°F | 63°F | 3.50 | 0.0 |
| Tuscola | 84°F | 63°F | 2.97 | 0.0 |
| Flora | 88°F | 63°F | 3.73 | 0.0 |
| Shelbyville | 85°F | 65°F | 3.41 | – |
| Watseka | 83°F | 60°F | 3.50 | 0.0 |
| Paxton | 83°F | 60°F | 3.47 | 0.0 |
| Lawrenceville | 87°F | 65°F | 2.94 | – |
| Sullivan | 85°F | 62°F | 3.16 | 0.0 |
| Anna | 89°F | 67°F | 3.15 | 0.0 |
| Pittsfield | 87°F | 64°F | 3.43 | 0.0 |
| Sparta | 87°F | 64°F | 3.54 | 0.0 |
| Dwight | 82°F | 59°F | 3.68 | 0.0 |
| Morrison | 81°F | 60°F | 4.32 | 0.0 |
| Fulton | 82°F | 63°F | 3.43 | – |
| Aledo | 83°F | 62°F | 3.89 | 0.0 |
| Gibson City | 83°F | 62°F | 3.64 | 0.0 |
| Carlyle | 87°F | 66°F | 3.59 | – |
| Galena | 80°F | 60°F | 4.19 | 0.0 |
| Virden | 85°F | 66°F | 3.09 | 0.0 |
| Nashville | 86°F | 65°F | 3.09 | 0.0 |
| Rushville | 83°F | 63°F | 3.75 | – |
| Knoxville | 82°F | 63°F | 3.50 | 0.0 |
| Havana | 86°F | 63°F | 4.02 | 0.0 |
| Newton | 85°F | 65°F | 3.06 | 0.0 |
| McLeansboro | 88°F | 63°F | 2.57 | 0.0 |
| Galva | 82°F | 60°F | 3.73 | – |
| Casey | 86°F | 64°F | 3.03 | 0.0 |
| Polo | 83°F | 59°F | 3.71 | – |
| White Hall | 84°F | 64°F | 3.35 | 0.0 |
| Petersburg | 85°F | 63°F | 3.66 | 0.0 |
| Mason City | 84°F | 62°F | 3.57 | 0.0 |
| Athens | 83°F | 62°F | 3.27 | – |
| Minonk | 84°F | 62°F | 3.48 | 0.0 |
| Albion | 88°F | 67°F | – | – |
| Lacon | 86°F | 63°F | 3.33 | 0.0 |
| Princeville | 84°F | 61°F | 3.70 | 0.0 |
| Chenoa | 82°F | 61°F | 3.17 | 0.0 |
| Stockton | 80°F | 59°F | 4.16 | 0.0 |
| Cairo | 88°F | 68°F | 3.18 | – |
| Winchester | 86°F | 63°F | 3.47 | – |
| Grayville | 88°F | 65°F | 3.64 | 0.0 |
| Mount Carroll | 83°F | 58°F | 3.91 | 0.0 |
| Neoga | 86°F | 62°F | 3.11 | – |
| Walnut | 82°F | 61°F | 3.83 | 0.0 |
| Palestine | 86°F | 64°F | 3.53 | 0.0 |
| La Harpe | 83°F | 63°F | 3.42 | – |
| Windsor | 84°F | 63°F | 2.95 | 0.0 |
| Morrisonville | 86°F | 64°F | 3.50 | 0.0 |
| Rosiclare | 86°F | 63°F | 3.24 | 0.0 |
| Ramsey | 85°F | 62°F | 3.57 | 0.0 |
| Shabbona | 80°F | 58°F | 4.08 | – |
| Paw Paw | 80°F | 60°F | 3.74 | 0.0 |
| Hennepin | 83°F | 62°F | 3.77 | – |
| Piper City | 85°F | 60°F | 4.14 | 0.0 |
| Ogden | 83°F | 63°F | 3.50 | 0.0 |
| Brookport | 88°F | 66°F | 2.93 | 0.0 |
| Elizabeth | 81°F | 59°F | 4.02 | 0.0 |
| Brownstown | 86°F | 64°F | 3.15 | – |
| Avon | 82°F | 60°F | 3.67 | 0.0 |
| Golden | 85°F | 63°F | – | – |
| New Boston | 84°F | 63°F | 3.83 | – |
| Congerville | 84°F | 63°F | 3.74 | 0.0 |
| Sidell | 83°F | 62°F | 3.25 | 0.0 |
| Altona | 82°F | 59°F | 3.76 | – |
| Prairie City | 84°F | 63°F | 3.21 | 0.0 |
| Perry | 86°F | 63°F | 3.21 | 0.0 |
| Compton | 81°F | 60°F | – | – |
| Gladstone | 84°F | 65°F | 3.60 | 0.0 |
| Bentley | 85°F | 64°F | 4.19 | 0.0 |
| Kaskaskia | 88°F | 66°F | 3.34 | 0.0 |
| Illinois City | 83°F | 63°F | 3.94 | – |
| Cahokia | 87°F | 67°F | 3.09 | 0.0 |
| Chicago Aurora Municipal Airport | 82°F | 60°F | 3.35 | – |
| Chicago Botanic Garden | 82°F | 62°F | 4.16 | 0.0 |
| Chicago Midway Airport | 83°F | 66°F | 3.99 | – |
| Chicago Waukegan Regional Airport | 80°F | 61°F | 3.59 | – |
| Dixon Springs Agricultural Center | 87°F | 65°F | 3.65 | 0.0 |
| Grand Chain Dam 53 | 89°F | 67°F | 3.03 | 0.0 |
| Iuka (12 mi SW) | 87°F | 64°F | 3.54 | 0.0 |
| Little Red School House | 87°F | 63°F | 4.46 | – |
| McHenry W.G. Stratton Lock and Dam | 82°F | 60°F | 3.70 | 0.0 |
| Rend Lake Dam | 87°F | 66°F | 3.35 | – |
| Smithland Lock and Dam | 87°F | 67°F | 2.79 | 0.0 |
Source: NOAA NCEI nClimDiv statewide normals; NOAA NCEI 1991-2020 monthly normals for each station.