Algonquin, in Illinois, United States, is home to roughly 30,600 people in the Central Time Zone at 42.2°N latitude.
In 2025, Algonquin recorded an average annual temperature of 50°F — about 1.1°F below the 30-year normal of 51°F. The hottest day reached 93°F in June; the coldest was -11°F in February. Total precipitation was 33 inches (near normal). The wettest month was June.
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