Jefferson County Climate
Jefferson County, Wisconsin
Avg Annual Temp
46.9°F
Annual Precip
37.2"
Annual Snowfall
40.1"
Extreme Heat Days
10.114285714285714
days >= 90°F/yr
Monthly Temperature
Precipitation Calendar
Seasonal Overview
National Comparison
Climate Profile
About Jefferson County Weather
Milder than the Northern Median
Jefferson County averages 46.9°F annually, staying well below the national median of 53.8°F. However, it is one of the warmer spots in the Upper Midwest region.
Warmer than the State Average
At 46.9°F, the county is 2.5 degrees warmer than the 44.4°F Wisconsin average. This makes it one of the more temperate locations for agriculture and residency in the state.
Middle Ground of Southern Wisconsin
Jefferson is slightly cooler than Kenosha County's 48.3°F but warmer than Iowa County's 45.7°F. Its 37.2 inches of rain exceeds the state average of 34.5 inches.
Steamy Summers and Snowy Winters
July averages a warm 71.8°F with 10 days of extreme heat reaching 90°F or higher. Winters are slightly milder than northern neighbors, averaging 22.3°F with 40.1 inches of snow.
Cooling and Drainage Focus
Effective air conditioning is recommended for the 10 annual extreme heat days. Homeowners should also ensure proper yard drainage to manage the 37.2 inches of annual precipitation.
Frequently Asked Questions
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Data source: NOAA National Centers for Environmental Information (NCEI), U.S. Climate Normals 1991-2020.
Climate normals are 30-year averages of weather variables computed from 1991 to 2020. Station data is aggregated to county level using spatial averaging. Data is informational only — not a substitute for official National Weather Service forecasts or emergency weather warnings.