Weather & Climate in Williams Bay, WI
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
Williams Bay experiences four distinct seasons with an average annual temperature of 49°F (10°C). Winters average 23°F in January while summers reach 74°F in July. Annual precipitation totals 36.9 inches. The area receives 40.1 inches of snow annually, making winter weather a significant factor for residents. Air quality is rated Good with a median AQI of 42. 82% of days have good air quality. The city sits at an elevation of 913 feet.
Temperature
23°F Jan (-5°C)
74°F Jul (24°C)
| Annual Average | 49.4°F |
| 9% below US avg | |
| January Average | 23°F (-5°C) |
| July Average | 74°F (24°C) |
Geography
| Elevation | 913 ft (278 m) |
| Area | 2.8 sq mi (7.3 km²) |
| Population Density | 1,067/sq mi |
| Coordinates | 42.5788°N, 88.5457°W |
| Timezone | America/Chicago |
| County | Walworth County County |
| Nearest Airport | Southern Wisconsin Regional (JVL) 25 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 42.0 |
| Rating | Good |
| Good Days % | 82.0% |
| Unhealthy Days | 0 |
Natural Hazard Risk
| Overall Risk | Relatively Low |
| Risk Score | 74.8 / 100 |
| Social Vulnerability | 20.8 / 100 |
| Community Resilience | 80.3 / 100 |
Hazard Breakdown
| Tornado | Relatively Moderate |
| Hurricane | Very Low |
| Earthquake | Very Low |
| Wildfire | Very Low |
| Flood | Relatively Moderate |
| Hail | Relatively High |
| Strong Wind | Relatively Moderate |
| Heat Wave | Relatively Low |
| Winter Weather | Relatively Low |
| Lightning | Relatively Moderate |
| Ice Storm | Relatively Low |
| Drought | Relatively Low |
| Cold Wave | Relatively Moderate |
| Landslide | Relatively Low |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Earthquake History
7 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 | 128 km | 10 km |
| Feb 10, 2010 | 2 km NW of Lily Lake, Illinois | M3.8 | 68 km | 10 km |
| Sep 2, 1999 | 8 km W of Amboy, Illinois | M3.5 | 120 km | 5 km |
| Nov 4, 2013 | 1 km SSW of Lyons, Illinois | M3.2 | 105 km | 1 km |
| Jul 15, 2024 | 2 km WNW of Somonauk, Illinois | M3.1 | 105 km | 10 km |
| Mar 25, 2015 | 3 km WNW of Lake in the Hills, Illinois | M2.9 | 46 km | 6 km |
| Jun 10, 2013 | 4 km NNE of Virgil, Illinois | M2.6 | 66 km | 5 km |
Source: USGS Earthquake Catalog (M2.5+, 1990-2025). Sorted by magnitude.
Tornado History
553 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF4. Total: 47 fatalities, 1,261 injuries.
| Date | Rating | Distance | Path | Fatalities |
| Apr 27, 1984 | EF4 | 47 km | 6.5 mi | 1 |
| Apr 4, 1981 | EF4 | 99 km | 1.8 mi | 3 |
| Sep 28, 1972 | EF4 | 65 km | 5.2 mi | 0 |
| Apr 21, 1967 | EF4 | 53 km | 8.8 mi | 1 |
| Apr 21, 1967 | EF4 | 50 km | 25.5 mi | 24 |
| Apr 11, 1965 | EF4 | 42 km | 9.1 mi | 6 |
| Jun 20, 2021 | EF3 | 97 km | 17.6 mi | 0 |
| Jun 16, 2014 | EF3 | 95 km | 1.0 mi | 0 |
| Jan 7, 2008 | EF3 | 31 km | 13.2 mi | 0 |
| Jan 7, 2008 | EF3 | 18 km | 10.8 mi | 0 |
| Aug 18, 2005 | EF3 | 82 km | 18.6 mi | 1 |
| Jun 17, 1992 | EF3 | 87 km | 16.0 mi | 0 |
| Jun 5, 1980 | EF3 | 64 km | 10.7 mi | 0 |
| Jun 4, 1975 | EF3 | 91 km | 2.3 mi | 0 |
| Aug 2, 1967 | EF3 | 96 km | 0.1 mi | 2 |
| Jan 24, 1967 | EF3 | 68 km | 24.9 mi | 0 |
| Jul 19, 1963 | EF3 | 24 km | 10.6 mi | 0 |
| Jun 22, 2024 | EF2 | 47 km | 6.0 mi | 0 |
| Feb 8, 2024 | EF2 | 66 km | 25.9 mi | 0 |
| Jun 16, 2014 | EF2 | 92 km | 0.2 mi | 0 |
Source: NOAA Storm Prediction Center (EF0+, 1950-2024, US only).
Wildfire History
3 wildfires (100+ acres) recorded within 100 km. Largest: IBSP SOUTH F1 RX (690 acres, 2024).
| Year | Name | Acres Burned | Distance |
| 2024 | IBSP SOUTH F1 RX | 690 | 63 km |
| 2024 | RX-HWY Y - SOUTH | 553 | 46 km |
| 2009 | COLD SPRINGS | 552 | 89 km |
Source: NIFC/IRWIN Wildfire Records (100+ acres).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 23°F (-5°C) | 1.9 in | Coldest |
| February | 26°F (-4°C) | 1.9 in | Driest |
| March | 36°F (2°C) | 2.3 in | |
| April | 48°F (9°C) | 3.5 in | |
| May | 60°F (16°C) | 4.1 in | |
| June | 70°F (21°C) | 4.8 in | Wettest |
| July | 74°F (24°C) | 3.7 in | Warmest |
| August | 72°F (22°C) | 3.3 in | |
| September | 65°F (18°C) | 3.7 in | |
| October | 52°F (11°C) | 3.0 in | |
| November | 39°F (4°C) | 2.5 in | |
| December | 28°F (-2°C) | 2.3 in |
Williams Bay has a seasonal temperature swing of 52°F / from 23°F in January to 74°F in July. Total annual precipitation is 37.0 inches, with June being the wettest month (4.8") and February the driest (1.9").