Climate

Four Seasons on the Lakes

St. Clair County, the easternmost of Michigan’s 83 counties, enjoys four distinct seasons, perhaps none lovelier than the pleasant summers that inspired one of the Midwest’s earliest vacation destinations.

Our climate is influenced by Lake Huron, which is nearly as large as West Virginia, and Lake St. Clair, the nation’s 15th largest lake. The moderating effect of the lakes tends to extend the growing season, particularly in autumn, and to create cooling breezes in the heat of summer.

The latter phenomenon helps explain why well-to-do residents of the Midwest’s larger cities, particularly St. Louis, flocked here for summer stays starting in the late 19th century. Visitors included Harry and Bess Truman, who honeymooned here.

An index developed by BestPlaces.net puts our summer comfort rating at 54, significantly better than the national average of 44. July, with an average high of 81, is our warmest month. January, with an average high of 30, is the coolest. On our lakes and rivers, water temperatures typically peak in the 70s in August.

Port Huron, the county seat, averages 32 inches of rain per year, just shy of the U.S. average of 37 inches. In an average winter, Port Huron receives 36 inches of snow. A lee shore tends to shelter us from lake-effect snowstorms. Northeasterlies, with winds blowing off Lake Huron, are the exception.