Hamilton County Climate
Hamilton County, Iowa
Avg Annual Temp
46.1°F
Annual Precip
36.6"
Annual Snowfall
30.4"
Extreme Heat Days
12.6
days >= 90°F/yr
Monthly Temperature
Precipitation Calendar
Seasonal Overview
National Comparison
Climate Profile
About Hamilton County Weather
A cold northern interior climate
Hamilton County is one of the cooler spots in the region, with an annual average of 46.1°F. Its 36.6 inches of precipitation aligns closely with national and state medians.
Colder than the Iowa average
At 46.1°F, Hamilton County is nearly two degrees colder than the state average of 48.0°F. Its 36.6 inches of annual precipitation is just above the Iowa norm of 36.1 inches.
Consistently colder than western neighbors
Hamilton is notably cooler than Greene County’s 47.8°F average. Its 30.4 inches of snowfall is also significantly lower than Fayette County’s 40.2 inches.
Deep winter freezes and mild heat
January is very cold with an average of 16.6°F, contributing to 30.4 inches of snow. Extreme heat is limited, with only 13 days per year reaching the 90°F threshold.
Winterize for the long haul
With a winter average of only 20.0°F, high-quality insulation and heating are paramount. Residents should also be prepared for over 30 inches of snow throughout the season.
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.