Johnson County Climate
Johnson County, Iowa
Avg Annual Temp
50.0°F
Annual Precip
37.1"
Annual Snowfall
28.4"
Extreme Heat Days
21.6
days >= 90°F/yr
Monthly Temperature
Precipitation Calendar
Seasonal Overview
National Comparison
Climate Profile
About Johnson County Weather
Johnson County's Variable Climate
Johnson County averages 50.0°F annually, falling just below the national median. This region is characterized by significant seasonal shifts and robust annual precipitation of 37.1 inches.
A Warm Spot in Iowa
Johnson is notably warmer than the state average, exceeding the 48.0°F Iowa norm by two degrees. It is also wetter than average, receiving 37.1 inches of rain and snow combined.
Warmer than Northern Neighbors
The county is three degrees warmer on average than Jones County to its north. It experiences 22 days of extreme heat, making it a warmer corridor in the eastern part of the state.
Hot Summers and Snowy Winters
July temperatures average 74.7°F, contributing to 22 extreme heat days over 90°F. Winters are cold, bringing 28.4 inches of snowfall and an average low of 21.6°F in January.
Equip for Heat and Ice
With over three weeks of 90°F weather, reliable cooling is essential for summer safety. Residents should also keep ice melt and snow shovels ready for the 28.4 inches of annual snow.
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.