Weather & Climate in Chillicothe, IL
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
Chillicothe experiences four distinct seasons with an average annual temperature of 53°F (11°C). Winters average 26°F in January while summers reach 76°F in July. Annual precipitation totals 36.4 inches. The area receives 20.0 inches of snow annually, a moderate snowfall amount. Air quality is rated Good with a median AQI of 44. 69% of days have good air quality. The city sits at an elevation of 535 feet.
Temperature
26°F Jan (-3°C)
76°F Jul (24°C)
| Annual Average | 52.6°F |
| 3% below US avg | |
| January Average | 26°F (-3°C) |
| July Average | 76°F (24°C) |
Geography
| Elevation | 535 ft (163 m) |
| Area | 5.3 sq mi (13.6 km²) |
| Population Density | 1,174/sq mi |
| Coordinates | 40.9160°N, 89.5027°W |
| Timezone | America/Chicago |
| County | Peoria County County |
| Nearest Airport | General Downing - Peoria International (PIA) 20 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 44.0 |
| Rating | Good |
| Good Days % | 68.6% |
| Unhealthy Days | 0 |
Natural Hazard Risk
| Overall Risk | Relatively Moderate |
| Risk Score | 90.7 / 100 |
| Social Vulnerability | 50.0 / 100 |
| Community Resilience | 93.6 / 100 |
Hazard Breakdown
| Tornado | Relatively High |
| Hurricane | Very Low |
| Earthquake | Relatively Low |
| Wildfire | Very Low |
| Flood | Relatively Moderate |
| Hail | Relatively High |
| Strong Wind | Relatively High |
| Heat Wave | Relatively Moderate |
| Winter Weather | Relatively High |
| Lightning | Relatively High |
| Ice Storm | Relatively High |
| Drought | Relatively Moderate |
| Cold Wave | Relatively High |
| Landslide | Relatively Moderate |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Earthquake History
6 earthquakes (M2.5+) recorded within 150 km since 1990. Strongest on record: M4.2.
| Jun 28, 2004 | 12 km NW of Dayton, Illinois | M4.2 | 79 km | 10 km |
| Feb 10, 2010 | 2 km NW of Lily Lake, Illinois | M3.8 | 144 km | 10 km |
| Sep 2, 1999 | 8 km W of Amboy, Illinois | M3.5 | 90 km | 5 km |
| Jul 15, 2024 | 2 km WNW of Somonauk, Illinois | M3.1 | 105 km | 10 km |
| Jun 10, 2013 | 4 km NNE of Virgil, Illinois | M2.6 | 145 km | 5 km |
| Mar 15, 2025 | 6 km W of Dwight, Illinois | M2.6 | 86 km | 5 km |
Source: USGS Earthquake Catalog (M2.5+, 1990-2025). Sorted by magnitude.
Tornado History
694 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF4. Total: 24 fatalities, 601 injuries.
| Date | Rating | Distance | Path | Fatalities |
| Nov 17, 2013 | EF4 | 33 km | 46.4 mi | 3 |
| Jul 13, 2004 | EF4 | 19 km | 9.6 mi | 0 |
| May 13, 1995 | EF4 | 91 km | 7.0 mi | 0 |
| Mar 29, 1981 | EF4 | 93 km | 5.1 mi | 0 |
| May 5, 1977 | EF4 | 77 km | 7.3 mi | 0 |
| Jun 29, 1976 | EF4 | 25 km | 4.9 mi | 0 |
| Apr 4, 2023 | EF3 | 95 km | 19.9 mi | 0 |
| Feb 28, 2017 | EF3 | 12 km | 17.8 mi | 0 |
| Feb 28, 2017 | EF3 | 65 km | 11.5 mi | 2 |
| Jun 5, 2010 | EF3 | 68 km | 8.6 mi | 0 |
| Apr 20, 2004 | EF3 | 42 km | 15.8 mi | 8 |
| May 10, 2003 | EF3 | 52 km | 17.5 mi | 0 |
| Apr 19, 1996 | EF3 | 68 km | 9.4 mi | 0 |
| May 13, 1995 | EF3 | 66 km | 25.0 mi | 0 |
| May 9, 1995 | EF3 | 49 km | 22.0 mi | 0 |
| Mar 13, 1990 | EF3 | 100 km | 15.5 mi | 0 |
| Jun 30, 1977 | EF3 | 85 km | 6.1 mi | 0 |
| Mar 4, 1976 | EF3 | 32 km | 0.8 mi | 0 |
| Jul 23, 1975 | EF3 | 81 km | 11.1 mi | 0 |
| Jul 23, 1975 | EF3 | 69 km | 14.0 mi | 2 |
Source: NOAA Storm Prediction Center (EF0+, 1950-2024, US only).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 26°F (-3°C) | 2.1 in | Coldest |
| February | 30°F (-1°C) | 1.9 in | Driest |
| March | 41°F (5°C) | 2.6 in | |
| April | 53°F (12°C) | 3.9 in | |
| May | 63°F (17°C) | 5.0 in | Wettest |
| June | 73°F (23°C) | 3.5 in | |
| July | 76°F (24°C) | 3.5 in | Warmest |
| August | 74°F (24°C) | 3.5 in | |
| September | 67°F (20°C) | 2.9 in | |
| October | 55°F (13°C) | 2.8 in | |
| November | 42°F (6°C) | 2.6 in | |
| December | 31°F (-1°C) | 2.1 in |
Chillicothe has a seasonal temperature swing of 50°F / from 26°F in January to 76°F in July. Total annual precipitation is 36.4 inches, with May being the wettest month (5.0") and February the driest (1.9").