Jefferson County Climate
Jefferson County, Iowa
NOAA NCEI 1991-2020 Climate NormalsAvg Annual Temp
49.7°F
Annual Precip
38.4"
Annual Snowfall
21.7"
Extreme Heat Days
24
days >= 90°F/yr
Monthly Temperature
Precipitation Calendar
Growing Season & Gardening
5b
Minimum winter temperature range for plant survival
3,143
Supports most vegetables & fruits
Seasonal Overview
National Comparison
7-Day Outlook
Forecast
Current Conditions
Air Quality
Safety
Weather Alerts
Climate Advisory: Jefferson County
Climate Verdict
Jefferson County has a cool, averaging 49.7°F annually, moderate rainfall of 38.4 inches per year, occasional hot days — 23.8 per year above 90°F, moderate snowfall of 21.7 inches annually. This climate profile shapes everything from energy costs to outdoor recreation opportunities.
Seasonal Breakdown
Winters are very cold — January averages 22.1°F. summers are warm — July averages 73.8°F. Residents experience a substantial 52°F difference between winter and summer.
Outdoor & Gardening Guidance
Growing season and gardening data is currently limited for Jefferson County. Check the USDA Plant Hardiness Zone Map and local extension office for specific guidance.
Regional Context
Jefferson County closely matches the Iowa statewide average temperature of 48.0°F, it is somewhat wetter than average for Iowa.
Climate Profile
About Jefferson County Weather
Jefferson's Warm Humid Continental Climate
Jefferson County averages 49.7°F annually, sitting below the national median but among the warmer spots in Iowa. It features a lush environment supported by 38.4 inches of rain.
Warmer and Wetter than Average
The county stays nearly two degrees warmer than the Iowa state average of 48.0°F. It also receives about two extra inches of precipitation compared to the 36.1-inch state norm.
High Heat Relative to Neighbors
Jefferson sees 24 extreme heat days per year, significantly more than the 16 days recorded in nearby Keokuk County. It remains warmer and wetter than central Iowa counties like Jasper.
Milder Winters and Toasty Summers
Winters are relatively mild for the region, averaging 25.4°F with 21.7 inches of snow. However, summers are intense, featuring 24 days where the mercury hits 90°F or higher.
Focus on Cooling and Drainage
The high number of extreme heat days makes efficient air conditioning a top priority. Homeowners should also maintain clear gutters to handle the heavy 38.4 inches of annual rainfall.
Frequently Asked Questions
What is the average temperature in Jefferson County?
How much rain does Jefferson County get?
Does it snow in Jefferson County?
How hot does Jefferson County get in summer?
How cold are winters in Jefferson County?
Track your own weather in Jefferson County
Ambient Weather personal weather stations give you hyperlocal climate data.
Sponsored
Data sources: NOAA National Centers for Environmental Information (NCEI), U.S. Climate Normals 1991-2020. Forecast and alert data from National Weather Service API. Air quality data from Open-Meteo.
Climate normals are 30-year averages of weather variables. Station data is aggregated to county level. Forecasts and alerts are fetched live and may change frequently. Data is informational only — not a substitute for official National Weather Service forecasts or emergency weather warnings.