Hamilton County Climate
Hamilton County, Iowa
NOAA NCEI 1991-2020 Climate NormalsAvg Annual Temp
46.1°F
Annual Precip
36.6"
Annual Snowfall
30.4"
Extreme Heat Days
13
days >= 90°F/yr
Monthly Temperature
Precipitation Calendar
Growing Season & Gardening
5a
Minimum winter temperature range for plant survival
2,678
Supports most vegetables & fruits
Seasonal Overview
National Comparison
7-Day Outlook
Forecast
Current Conditions
Air Quality
Safety
Weather Alerts
Climate Advisory: Hamilton County
Climate Verdict
Hamilton County has a cool, averaging 46.1°F annually, moderate rainfall of 36.6 inches per year, rare extreme heat with only 12.6 days above 90°F annually, moderate snowfall of 30.4 inches annually. This climate profile shapes everything from energy costs to outdoor recreation opportunities.
Seasonal Breakdown
Winters are very cold — January averages 16.6°F. summers are warm — July averages 71.8°F. Residents experience a substantial 55°F difference between winter and summer.
Outdoor & Gardening Guidance
Growing season and gardening data is currently limited for Hamilton County. Check the USDA Plant Hardiness Zone Map and local extension office for specific guidance.
Regional Context
Hamilton County closely matches the Iowa statewide average temperature of 48.0°F.
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 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.