Assumption is a city of approximately 1,100 people in Illinois, United States. Located in the Central Time Zone at 39.5°N latitude.
In 2025, Assumption recorded an average annual temperature of 55°F — about 1.4°F above the 30-year normal of 53°F. The hottest day reached 96°F in September; the coldest was -4°F in January. Total precipitation was 31 inches (drier than usual). The wettest month was April.
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