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Weather & Climate in Winnebago, IL
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
Winnebago experiences four distinct seasons with an average annual temperature of 49°F (10°C). Winters average 22°F in January while summers reach 74°F in July. The area gets 260 sunny days per year, above the national average. Annual precipitation totals 37.2 inches. The area receives 37.1 inches of snow annually, a moderate snowfall amount. Air quality is rated Good with a median AQI of 43. 69% of days have good air quality. The city sits at an elevation of 870 feet.
Temperature
22°F Jan (-6°C)
74°F Jul (23°C)
| Annual Average | 49.4°F |
| 9% below US avg | |
| January Average | 22°F (-6°C) |
| July Average | 74°F (23°C) |
| Sunny Days | 260 days/yr |
Geography
| Elevation | 870 ft (265 m) |
| Area | 0.8 sq mi (1.9 km²) |
| Population Density | 1,501/sq mi |
| Coordinates | 42.2671°N, 89.2340°W |
| Timezone | America/Chicago |
| County | Winnebago County County |
| Nearest Airport | Chicago/Rockford International (RFD) 9 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 43.0 |
| Rating | Good |
| Good Days % | 69.0% |
| Unhealthy Days | 3 |
Natural Hazard Risk
| Overall Risk | Relatively Moderate |
| Risk Score | 92.4 / 100 |
| Social Vulnerability | 38.9 / 100 |
| Community Resilience | 68.5 / 100 |
Hazard Breakdown
| Tornado | Relatively High |
| Hurricane | Very Low |
| Earthquake | Relatively Low |
| Wildfire | Very Low |
| Flood | Relatively High |
| Hail | Relatively High |
| Strong Wind | Relatively High |
| Heat Wave | Relatively Moderate |
| Winter Weather | Relatively Moderate |
| Lightning | Relatively High |
| Ice Storm | Relatively High |
| Drought | Relatively Low |
| Cold Wave | Relatively High |
| Landslide | Very Low |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Earthquake History
8 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 | 94 km | 10 km |
| Feb 10, 2010 | 2 km NW of Lily Lake, Illinois | M3.8 | 69 km | 10 km |
| Sep 2, 1999 | 8 km W of Amboy, Illinois | M3.5 | 63 km | 5 km |
| Nov 4, 2013 | 1 km SSW of Lyons, Illinois | M3.2 | 128 km | 1 km |
| Jul 15, 2024 | 2 km WNW of Somonauk, Illinois | M3.1 | 81 km | 10 km |
| Mar 25, 2015 | 3 km WNW of Lake in the Hills, Illinois | M2.9 | 72 km | 6 km |
| Jun 10, 2013 | 4 km NNE of Virgil, Illinois | M2.6 | 67 km | 5 km |
| Mar 15, 2025 | 6 km W of Dwight, Illinois | M2.6 | 145 km | 5 km |
Source: USGS Earthquake Catalog (M2.5+, 1990–2025). Sorted by magnitude.
Tornado History
576 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF5. Total: 82 fatalities, 1,496 injuries.
| Date | Rating | Distance | Path | Fatalities |
| Aug 28, 1990 | EF5 | 98 km | 16.4 mi | 29 |
| Jun 7, 1984 | EF5 | 99 km | 36.0 mi | 9 |
| Apr 9, 2015 | EF4 | 46 km | 30.1 mi | 2 |
| Mar 29, 1981 | EF4 | 88 km | 5.1 mi | 0 |
| Apr 21, 1967 | EF4 | 81 km | 8.8 mi | 1 |
| Apr 21, 1967 | EF4 | 26 km | 25.5 mi | 24 |
| Apr 11, 1965 | EF4 | 71 km | 9.1 mi | 6 |
| Jun 16, 2014 | EF3 | 86 km | 1.0 mi | 0 |
| Jan 7, 2008 | EF3 | 81 km | 10.8 mi | 0 |
| Jan 7, 2008 | EF3 | 36 km | 13.2 mi | 0 |
| Aug 18, 2005 | EF3 | 74 km | 18.6 mi | 1 |
| Jun 17, 1992 | EF3 | 72 km | 16.0 mi | 0 |
| May 8, 1988 | EF3 | 89 km | 16.0 mi | 0 |
| Aug 5, 1979 | EF3 | 40 km | 5.7 mi | 0 |
| Jun 30, 1977 | EF3 | 79 km | 6.1 mi | 0 |
| Jun 20, 1974 | EF3 | 91 km | 10.6 mi | 1 |
| Aug 2, 1967 | EF3 | 98 km | 0.1 mi | 2 |
| Apr 16, 1967 | EF3 | 64 km | 27.8 mi | 0 |
| Jan 24, 1967 | EF3 | 70 km | 7.4 mi | 0 |
| Jan 24, 1967 | EF3 | 39 km | 24.9 mi | 0 |
Source: NOAA Storm Prediction Center (EF0+, 1950–2024, US only).
Wildfire History
2 wildfires (100+ acres) recorded within 100 km. Largest: RX-HWY Y - SOUTH (553 acres, 2024).
| Year | Name | Acres Burned | Distance |
| 2024 | RX-HWY Y - SOUTH | 553 | 87 km |
| 2009 | COLD SPRINGS | 552 | 56 km |
Source: NIFC/IRWIN Wildfire Records (100+ acres).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 22°F (-6°C) | 1.3 in | Coldest |
| February | 23°F (-5°C) | 1.1 in | Driest |
| March | 35°F (2°C) | 2.4 in | |
| April | 47°F (8°C) | 3.5 in | |
| May | 59°F (15°C) | 3.7 in | |
| June | 68°F (20°C) | 4.4 in | Wettest |
| July | 74°F (23°C) | 3.8 in | Warmest |
| August | 70°F (21°C) | 4.1 in | |
| September | 62°F (17°C) | 3.8 in | |
| October | 51°F (10°C) | 2.7 in | |
| November | 37°F (3°C) | 2.6 in | |
| December | 24°F (-5°C) | 2.0 in |
Winnebago has a seasonal temperature swing of 52°F / from 22°F in January to 74°F in July. Total annual precipitation is 35.4 inches, with June being the wettest month (4.4") and February the driest (1.1").