Johnston City is a city of approximately 3,500 people in Illinois, United States. Located in the Central Time Zone at 37.8°N latitude.
In 2025, Johnston City recorded an average annual temperature of 58°F — about 1.3°F above the 30-year normal of 56°F. The hottest day reached 95°F in July; the coldest was 2°F in February. Total precipitation was 46 inches (near normal). The wettest month was April.
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