Fairfield is a city of approximately 5,300 people in Illinois, United States. Located in the Central Time Zone at 42.2°N latitude.
In 2025, Fairfield recorded an average annual temperature of 50°F — about 1.1°F below the 30-year normal of 51°F. The hottest day reached 94°F in August; the coldest was -10°F in February. Total precipitation was 34 inches (wetter than usual). The wettest month was June.
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