The national lakeshore's weather is greatly affected by Lake Michigan and can change quickly. Summers are warm and humid with high temperatures generally in the mid-80sºF (30C) and low temperatures in the mid-60sºF (18C). There are about 15 days per year above 90ºF (32C). Warm periods are occasionally interrupted by frontal action descending from Canada. This generally brings days of pleasant, dry weather. Sunshine is abundant in summer. Highs in winter are usually in the low to mid 30sºF (0C) with low temperatures in the low 20sºF (-5C). There are about 15 days per year below 0ºF (-18C). Winters tend to be cloudy except for periods of extreme cold when skies are clear.
For a current weather forecast choose an Internet weather provider and use the following zip codes for the section of the park you are interested in.
Did You Know?
Cowles Bog is not a true bog but rather a fen because it has an underground water source. This water source has contact with limestone bedrock, making the fen’s water slightly alkaline. Indiana Dunes National Lakeshore is restoring a portion of this fen.