About Cortland, IL's Climate & Weather History

Cortland, in Illinois, United States, is home to roughly 4,300 people in the Central Time Zone at 41.9°N latitude.

In 2025, Cortland recorded an average annual temperature of 50°F — about 2.3°F above the 30-year normal of 48°F. The hottest day reached 92°F in June; the coldest was -12°F in February. Total precipitation was 31 inches (drier than usual). The wettest month was July.