With a population of around 5,400, Eureka sits in Illinois, United States. The city operates in the Central Time Zone.
In 2025, Eureka recorded an average annual temperature of 53°F — right at the 30-year normal of 53°F. The hottest day reached 91°F in May; the coldest was -9°F in January. Total precipitation was 31 inches (drier than usual). Snowfall totaled 8 inches, below the 26-inch average. The wettest month was July.
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