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Weather & Climate in Jefferson, WI
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
Jefferson experiences four distinct seasons with an average annual temperature of 47°F (9°C). Winters average 19°F in January while summers reach 73°F in July. The area gets 260 sunny days per year, above the national average. Annual precipitation totals 37.0 inches. The area receives 42.3 inches of snow annually, making winter weather a significant factor for residents. Air quality is rated Good with a median AQI of 39. 89% of days have good air quality. The city sits at an elevation of 798 feet.
Temperature
19°F Jan (-7°C)
73°F Jul (23°C)
| Annual Average | 47.4°F |
| 12% below US avg | |
| January Average | 19°F (-7°C) |
| July Average | 73°F (23°C) |
| Sunny Days | 260 days/yr |
Geography
| Elevation | 798 ft (243 m) |
| Area | 5.9 sq mi (15.4 km²) |
| Population Density | 1,325/sq mi |
| Coordinates | 43.0040°N, 88.8085°W |
| Timezone | America/Chicago |
| County | Jefferson County County |
| Nearest Airport | Dane County Regional/Truax Field (MSN) 28 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 39.0 |
| Rating | Good |
| Good Days % | 89.3% |
| Unhealthy Days | 0 |
Natural Hazard Risk
| Overall Risk | Relatively Low |
| Risk Score | 75.8 / 100 |
| Social Vulnerability | 19.8 / 100 |
| Community Resilience | 92.1 / 100 |
Hazard Breakdown
| Tornado | Relatively Moderate |
| Hurricane | Very Low |
| Earthquake | Very Low |
| Wildfire | Very Low |
| Flood | Relatively Moderate |
| Hail | Relatively Moderate |
| 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 | Very Low |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Earthquake History
3 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 | 118 km | 10 km |
| Mar 25, 2015 | 3 km WNW of Lake in the Hills, Illinois | M2.9 | 98 km | 6 km |
| Jun 10, 2013 | 4 km NNE of Virgil, Illinois | M2.6 | 115 km | 5 km |
Source: USGS Earthquake Catalog (M2.5+, 1990–2025). Sorted by magnitude.
Tornado History
557 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF5. Total: 55 fatalities, 1,362 injuries.
| Date | Rating | Distance | Path | Fatalities |
| Jul 18, 1996 | EF5 | 79 km | 13.3 mi | 0 |
| Jun 7, 1984 | EF5 | 95 km | 36.0 mi | 9 |
| Apr 27, 1984 | EF4 | 36 km | 6.5 mi | 1 |
| Apr 4, 1981 | EF4 | 68 km | 1.8 mi | 3 |
| Apr 21, 1974 | EF4 | 83 km | 26.0 mi | 0 |
| Apr 21, 1967 | EF4 | 88 km | 25.5 mi | 24 |
| Apr 11, 1965 | EF4 | 94 km | 9.1 mi | 6 |
| Aug 22, 1964 | EF4 | 83 km | 2.2 mi | 0 |
| Sep 26, 1951 | EF4 | 63 km | 9.0 mi | 1 |
| Jun 16, 2014 | EF3 | 61 km | 1.0 mi | 0 |
| Jan 7, 2008 | EF3 | 68 km | 13.2 mi | 0 |
| Jan 7, 2008 | EF3 | 64 km | 10.8 mi | 0 |
| Aug 18, 2005 | EF3 | 51 km | 18.6 mi | 1 |
| Jun 23, 2004 | EF3 | 75 km | 7.6 mi | 1 |
| Jun 23, 2004 | EF3 | 82 km | 33.3 mi | 0 |
| Jun 17, 1992 | EF3 | 60 km | 16.0 mi | 0 |
| Jun 8, 1984 | EF3 | 60 km | 29.0 mi | 0 |
| Jun 5, 1980 | EF3 | 14 km | 10.7 mi | 0 |
| Apr 7, 1980 | EF3 | 55 km | 1.2 mi | 0 |
| Jun 5, 1977 | EF3 | 91 km | 69.5 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 | 60 km |
| 2010 | RX BURN | 1,236 | 60 km |
| 1994 | SOMMERS | 938 | 63 km |
| 1988 | PEACHY RD | 812 | 60 km |
| 2018 | 2018 BADGER RX BURNS | 659 | 87 km |
| 2019 | 2019 BADGER RX BURNS | 627 | 86 km |
| 2006 | UNNAMED | 612 | 65 km |
| 2007 | TOWER RD 2 | 592 | 60 km |
| 2024 | RX-HWY Y - SOUTH | 553 | 7 km |
| 2009 | COLD SPRINGS | 552 | 76 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) | 3.1 in | |
| May | 58°F (15°C) | 3.1 in | |
| June | 67°F (20°C) | 3.9 in | |
| July | 73°F (23°C) | 4.1 in | Warmest, Wettest |
| August | 69°F (21°C) | 4.0 in | |
| September | 61°F (16°C) | 3.8 in | |
| October | 50°F (10°C) | 2.6 in | |
| November | 36°F (2°C) | 2.3 in | |
| December | 23°F (-5°C) | 1.7 in |
Jefferson has a seasonal temperature swing of 54°F / from 19°F in January to 73°F in July. Total annual precipitation is 33.2 inches, with July being the wettest month (4.1") and February the driest (1.1").