Somonauk, in Illinois, United States, is home to roughly 1,900 people in the Central Time Zone at 41.6°N latitude.
In 2025, Somonauk recorded an average annual temperature of 51°F — about 1.7°F above the 30-year normal of 49°F. The hottest day reached 92°F in June; the coldest was -10°F in February. Total precipitation was 34 inches (near normal). The wettest month was July.
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