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Weather & Climate in Lake Koshkonong, WI
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
Lake Koshkonong experiences four distinct seasons with an average annual temperature of 47°F (9°C). Winters average 19°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 35.5 inches. The area receives 36.4 inches of snow annually, a moderate snowfall amount. Air quality is rated Good with a median AQI of 38. The city sits at an elevation of 791 feet.
Temperature
19°F Jan (-7°C)
72°F Jul (22°C)
| Annual Average | 47.3°F |
| 12% below US avg | |
| January Average | 19°F (-7°C) |
| July Average | 72°F (22°C) |
| Sunny Days | 260 days/yr |
Geography
| Elevation | 791 ft (241 m) |
| Area | 29.8 sq mi (77.3 km²) |
| Population Density | 70/sq mi |
| Coordinates | 42.8605°N, 88.9401°W |
| Timezone | America/Chicago |
| County | Walworth County County |
| Nearest Airport | Southern Wisconsin Regional (JVL) 17 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 38.0 |
| Rating | Good |
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
6 earthquakes (M2.5+) recorded within 150 km since 1990. Strongest on record: M3.8.
| Feb 10, 2010 | 2 km NW of Lily Lake, Illinois | M3.8 | 106 km | 10 km |
| Sep 2, 1999 | 8 km W of Amboy, Illinois | M3.5 | 133 km | 5 km |
| Nov 4, 2013 | 1 km SSW of Lyons, Illinois | M3.2 | 149 km | 1 km |
| Jul 15, 2024 | 2 km WNW of Somonauk, Illinois | M3.1 | 136 km | 10 km |
| Mar 25, 2015 | 3 km WNW of Lake in the Hills, Illinois | M2.9 | 88 km | 6 km |
| Jun 10, 2013 | 4 km NNE of Virgil, Illinois | M2.6 | 103 km | 5 km |
Source: USGS Earthquake Catalog (M2.5+, 1990–2025). Sorted by magnitude.
Tornado History
572 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF5. Total: 57 fatalities, 1,465 injuries.
| Date | Rating | Distance | Path | Fatalities |
| Jul 18, 1996 | EF5 | 97 km | 13.3 mi | 0 |
| Jun 7, 1984 | EF5 | 86 km | 36.0 mi | 9 |
| Apr 27, 1984 | EF4 | 48 km | 6.5 mi | 1 |
| Jul 3, 1983 | EF4 | 98 km | 0.5 mi | 0 |
| Apr 4, 1981 | EF4 | 87 km | 1.8 mi | 3 |
| Apr 21, 1974 | EF4 | 99 km | 26.0 mi | 0 |
| Apr 21, 1967 | EF4 | 96 km | 8.8 mi | 1 |
| Apr 21, 1967 | EF4 | 71 km | 25.5 mi | 24 |
| Apr 11, 1965 | EF4 | 85 km | 9.1 mi | 6 |
| Sep 26, 1951 | EF4 | 72 km | 9.0 mi | 1 |
| Jun 16, 2014 | EF3 | 53 km | 1.0 mi | 0 |
| Jan 7, 2008 | EF3 | 53 km | 13.2 mi | 0 |
| Jan 7, 2008 | EF3 | 61 km | 10.8 mi | 0 |
| Aug 18, 2005 | EF3 | 41 km | 18.6 mi | 1 |
| Jun 23, 2004 | EF3 | 96 km | 33.3 mi | 0 |
| Jun 23, 2004 | EF3 | 90 km | 7.6 mi | 1 |
| Jun 17, 1992 | EF3 | 48 km | 16.0 mi | 0 |
| Jun 8, 1984 | EF3 | 70 km | 29.0 mi | 0 |
| Jun 5, 1980 | EF3 | 33 km | 10.7 mi | 0 |
| Apr 7, 1980 | EF3 | 69 km | 1.2 mi | 0 |
Source: NOAA Storm Prediction Center (EF0+, 1950–2024, US only).
Wildfire History
10 wildfires (100+ acres) recorded within 100 km. Largest: UNNAMED (1,524 acres, 2006).
| Year | Name | Acres Burned | Distance |
| 2006 | UNNAMED | 1,524 | 78 km |
| 2010 | RX BURN | 1,236 | 78 km |
| 1994 | SOMMERS | 938 | 81 km |
| 1988 | PEACHY RD | 812 | 78 km |
| 2018 | 2018 BADGER RX BURNS | 659 | 87 km |
| 2019 | 2019 BADGER RX BURNS | 627 | 86 km |
| 2006 | UNNAMED | 612 | 83 km |
| 2007 | TOWER RD 2 | 592 | 78 km |
| 2024 | RX-HWY Y - SOUTH | 553 | 20 km |
| 2009 | COLD SPRINGS | 552 | 60 km |
Source: NIFC/IRWIN Wildfire Records (100+ acres).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 19°F (-7°C) | 1.2 in | Coldest |
| February | 22°F (-5°C) | 1.1 in | Driest |
| March | 34°F (1°C) | 2.2 in | |
| April | 46°F (8°C) | 3.2 in | |
| May | 58°F (15°C) | 3.1 in | |
| June | 68°F (20°C) | 3.7 in | |
| July | 72°F (22°C) | 4.0 in | Warmest, Wettest |
| August | 70°F (21°C) | 3.9 in | |
| September | 62°F (16°C) | 3.8 in | |
| October | 50°F (10°C) | 2.5 in | |
| November | 37°F (3°C) | 2.3 in | |
| December | 24°F (-5°C) | 1.7 in |
Lake Koshkonong has a seasonal temperature swing of 53°F / from 19°F in January to 72°F in July. Total annual precipitation is 32.8 inches, with July being the wettest month (4.0") and February the driest (1.1").