St. Clair County Climate
St. Clair County, Michigan
NOAA NCEI 1991-2020 Climate NormalsAvg Annual Temp
47.9°F
Annual Precip
33.6"
Annual Snowfall
38.1"
Extreme Heat Days
12
days >= 90°F/yr
Monthly Temperature
Precipitation Calendar
Growing Season & Gardening
6a
Minimum winter temperature range for plant survival
2,608
Supports most vegetables & fruits
Seasonal Overview
National Comparison
7-Day Outlook
Forecast
Current Conditions
Air Quality
Safety
Weather Alerts
Climate Advisory: St. Clair County
Climate Verdict
St. Clair County has a cool, averaging 47.9°F annually, moderate rainfall of 33.6 inches per year, rare extreme heat with only 11.766666666666666 days above 90°F annually, moderate snowfall of 38.1 inches annually. This climate profile shapes everything from energy costs to outdoor recreation opportunities.
Seasonal Breakdown
Winters are very cold — January averages 23.6°F. summers are warm — July averages 71.6°F. The 48°F seasonal variation provides noticeable but manageable change.
Outdoor & Gardening Guidance
Growing season and gardening data is currently limited for St. Clair County. Check the USDA Plant Hardiness Zone Map and local extension office for specific guidance.
Regional Context
St. Clair County closely matches the Michigan statewide average temperature of 45.7°F.
Climate Profile
About St. Clair County Weather
A Classic Cool Continental Climate
St. Clair County averages 47.9°F annually, sitting roughly six degrees cooler than the national median temperature. This humid continental climate experiences significant seasonal swings compared to more temperate regions across the United States.
Warmer Than the Michigan Average
The county's 47.9°F average temperature puts it above the statewide Michigan average of 45.7°F. It ranks among the warmer tier of counties in the state, benefiting from its southern positioning and lake proximity.
Milder Than Northern Neighbors
St. Clair is significantly warmer than northern neighbor Tuscola County, which averages 46.3°F. However, it stays cooler than Wayne County to the south, where temperatures average a higher 50.1°F.
Swinging Between Lake Breezes and Snow
Summer highs reach a pleasant 71.6°F in July, though the area still sees about 12 extreme heat days over 90°F annually. Winters are brisk with a 23.6°F January average and 38.1 inches of total snowfall.
Prepare for Seasonal Transitions
Residents need robust heating systems for the sub-freezing winter average of 26.1°F. Reliable snow removal gear is essential to manage the 38 inches of annual accumulation that impacts winter commutes.
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.