The Great Lakes provide a mixing zone for tropical and polar air masses. Seasonal climatic changes are one of Michigan’s most important features. The southwest part of Michigan can receive between 40-45 inches of precipitation annually. In comparison, the Huron River basin in southeast Michigan is located in a relatively dry area and receives an average of 30 inches of precipitation annually. Seasonal precipitation patterns are fairly stable because the warmer temperatures tend to hold more moisture in the air.
As a result of southeast Michigan’s higher temperatures and slightly drier air, moisture evaporation in the Huron River Watershed is higher and annual water runoff is lower than in most of the rest of the state. Climate data gathered over a 30-year period indicate that average high temperatures in the watershed range from 32ºF (January) to 84ºF (July), and average low temperatures range from 15ºF (January) to 59ºF (July).