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Weather & Climate in Willow Lake, IL

Temperature, precipitation, air quality, natural hazards, and monthly weather data.

Willow Lake experiences four distinct seasons with an average annual temperature of 48°F (9°C). Winters average 20°F in January while summers reach 72°F in July. The area gets 260 sunny days per year, above the national average. Annual precipitation totals 38.4 inches. The area receives 34.5 inches of snow annually, a moderate snowfall amount. Air quality is rated Good with a median AQI of 43. The city sits at an elevation of 809 feet.

Temperature

20°F Jan (-7°C) 72°F Jul (22°C)
Annual Average47.7°F
12% below US avg
January Average20°F (-7°C)
July Average72°F (22°C)
Sunny Days260 days/yr

Geography

Elevation809 ft (247 m)
Area2.7 sq mi (7.1 km²)
Population Density307/sq mi
Coordinates42.3342°N, 89.6353°W
TimezoneAmerica/Chicago
CountyStephenson County County
Nearest AirportChicago/Rockford International (RFD)
29 miles away

Precipitation & Snow

Annual Rainfall 38.4"
1% above US avg
Snowfall 34.5"
Wettest Month (Jun) 4.13"
Driest Month (Feb) 1.14"

Air Quality

AQI Median43.0
RatingGood

Natural Hazard Risk

Overall RiskRelatively Low
Risk Score73.9 / 100
Social Vulnerability56.7 / 100
Community Resilience68.6 / 100

Hazard Breakdown

Tornado Relatively Moderate
Hurricane Very Low
Earthquake Very Low
Wildfire Very Low
Flood Relatively Moderate
Hail Relatively Moderate
Strong Wind Relatively High
Heat Wave Relatively Low
Winter Weather Relatively Low
Lightning Relatively Low
Ice Storm Relatively Moderate
Drought Relatively Moderate
Cold Wave Relatively Moderate
Landslide Very Low
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 M4.2 115 km 10 km
Feb 10, 2010 2 km NW of Lily Lake, Illinois M3.8 102 km 10 km
Sep 2, 1999 8 km W of Amboy, Illinois M3.5 70 km 5 km
Jul 15, 2024 2 km WNW of Somonauk, Illinois M3.1 108 km 10 km
Mar 25, 2015 3 km WNW of Lake in the Hills, Illinois M2.9 106 km 6 km
Jun 10, 2013 4 km NNE of Virgil, Illinois M2.6 100 km 5 km
Source: USGS Earthquake Catalog (M2.5+, 1990–2025). Sorted by magnitude.

Tornado History

565 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF5. Total: 46 fatalities, 951 injuries.

Date Rating Distance Path Fatalities
Jun 7, 1984 EF5 76 km 36.0 mi 9
Apr 9, 2015 EF4 61 km 30.1 mi 2
Jul 3, 1983 EF4 82 km 0.5 mi 0
Mar 29, 1981 EF4 77 km 5.1 mi 0
Apr 21, 1967 EF4 60 km 25.5 mi 24
Jun 16, 2014 EF3 75 km 1.0 mi 0
Jan 7, 2008 EF3 67 km 13.2 mi 0
Aug 18, 2005 EF3 67 km 18.6 mi 1
Jun 19, 1993 EF3 89 km 14.0 mi 0
Jun 17, 1992 EF3 61 km 16.0 mi 0
Mar 13, 1990 EF3 98 km 15.5 mi 0
May 8, 1988 EF3 56 km 16.0 mi 0
Aug 5, 1979 EF3 35 km 5.7 mi 0
Jun 30, 1977 EF3 99 km 6.1 mi 0
Jun 20, 1974 EF3 66 km 10.6 mi 1
Sep 9, 1970 EF3 87 km 4.7 mi 0
Aug 2, 1967 EF3 90 km 0.1 mi 2
Apr 16, 1967 EF3 32 km 27.8 mi 0
Jan 24, 1967 EF3 37 km 24.9 mi 0
Jan 24, 1967 EF3 45 km 7.4 mi 0
Source: NOAA Storm Prediction Center (EF0+, 1950–2024, US only).

Wildfire History

1 wildfire (100+ acres) recorded within 100 km. Largest: COLD SPRINGS (552 acres, 2009).

Year Name Acres Burned Distance
2009 COLD SPRINGS 552 38 km
Source: NIFC/IRWIN Wildfire Records (100+ acres).

Monthly Weather

Month Avg Temperature Precipitation Summary
January 20°F (-7°C) 1.2 in Coldest
February 22°F (-6°C) 1.1 in Driest
March 34°F (1°C) 2.3 in
April 47°F (8°C) 3.2 in
May 58°F (15°C) 3.7 in
June 68°F (20°C) 4.1 in Wettest
July 72°F (22°C) 3.7 in Warmest
August 69°F (21°C) 4.1 in
September 62°F (16°C) 3.9 in
October 50°F (10°C) 2.6 in
November 36°F (2°C) 2.4 in
December 23°F (-5°C) 1.8 in

Willow Lake has a seasonal temperature swing of 53°F / from 20°F in January to 72°F in July. Total annual precipitation is 34.1 inches, with June being the wettest month (4.1") and February the driest (1.1").

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