St. Clair County Climate
St. Clair County, Michigan
Avg Annual Temp
47.9°F
Annual Precip
33.6"
Annual Snowfall
38.1"
Extreme Heat Days
11.766666666666666
days >= 90°F/yr
Monthly Temperature
Precipitation Calendar
Seasonal Overview
National Comparison
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 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.