Grayslake is a city of approximately 20,900 people in Illinois, United States. Located in the Central Time Zone at 42.3°N latitude.
In 2025, Grayslake recorded an average annual temperature of 50°F — about 1.2°F above the 30-year normal of 48°F. The hottest day reached 94°F in July; the coldest was -10°F in February. Total precipitation was 33 inches (drier than usual). The wettest month was July.
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