July weather forecast and climate
Illinois, USA

Flag of Illinois, USA
Flag of Illinois, USA

Weather in July

July is by far the hottest month of the year in Illinois with the highest number of sunny days. The average high temperatures in the state are in the hot 82°F (27.8°C) to 89°F (31.7°C), while the nights are comparatively mild between 62°F (16.7°C) to 69°F (20.6°C). Day temperatures reach 90°F (32.2°C) to 100°F (37.8°C) in the event of a heatwave at the peak of summer. Peoria in central Illinois registers temperatures between 66°F (18.9°C) to 86°F (30°C), while Cairo in the south is between 66°F (18.9°C) to 89°F (31.7°C).
The 4" (102mm) to 5" (127mm) of precipitation is mainly due to thunderstorms that are prominent during summer. Expect humidity to rise rapidly and increase the overall heat index. Fishing, swimming, and boating are popular with many creeks, lakes, and rivers in the state. It is better to stay in the shade during afternoons when the heat is at its peak.
Wear sunglasses and large-brimmed hats on outdoor adventures such as hiking and trailing in the hills and mountains. Beware of extreme temperatures in July in Illinois.


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