With a population of around 1,300, Harristown sits in Illinois, United States. The city operates in the Central Time Zone.
In 2025, Harristown recorded an average annual temperature of 54°F — about 1.2°F above the 30-year normal of 53°F. The hottest day reached 93°F in September; the coldest was -5°F in January. Total precipitation was 30 inches (drier than usual). The wettest month was April.
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