Decatur County Climate
Decatur County, Iowa
Avg Annual Temp
50.9°F
Annual Precip
39.2"
Annual Snowfall
27.6"
Extreme Heat Days
21.4
days >= 90°F/yr
Monthly Temperature
Precipitation Calendar
Seasonal Overview
National Comparison
Climate Profile
About Decatur County Weather
High Precipitation and Moderate Temps
Decatur County averages 50.9°F annually, placing it among the more temperate counties in the American Midwest. Its 39.2 inches of annual precipitation is well above the national average, ensuring a lush but humid environment. This climate supports varied agriculture but requires residents to manage significant moisture throughout the year.
Leading the State in Warmth
At 50.9°F, Decatur County sits nearly 3 degrees above the Iowa state average of 48.0°F. It also outpaces the state average for rainfall, receiving 39.2 inches compared to the 36.1-inch norm. This makes the county part of the 'Banana Belt' of Iowa's southern tier.
Matching the Southern Iowa Profile
Decatur County's climate is nearly identical to Davis County, with both averaging roughly 51°F and 39 inches of rain. These counties are significantly warmer than central Iowa hubs like Dallas County. The southern border proximity results in 21 days of 90-degree heat, a common trend among its regional neighbors.
Steamy Summers and Snowy Decembers
Summer in Decatur County is defined by a 73.5°F average and 21 days of temperatures over 90°F. Winter is equally active, delivering 27.6 inches of snow and a January average of 23.5°F. The seasonal transition is marked by heavy precipitation, as seen in the high annual rainfall totals.
Equip for a Dynamic Climate
Residents need high-capacity cooling systems to combat the frequent 90-degree summer days. Winter preparation requires tools to manage nearly 28 inches of snow, particularly during the 26.6°F winter months. Given the high annual precipitation, investing in waterproof outdoor gear and home drainage is a smart move.
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.