Joliet Weather in August

The climate in Joliet during August can be summarized as warm, humid and a little damp.

August is in the summer in Joliet and is typically the 2nd warmest month of the year. Daytime maximum temperatures average around a muggy 28°C (82°F), whilst at night 16°C (61°F) is normal.

On average August is the 4th wettest month of the year in Joliet with around 94mm 3.7 inches of rain making it a a little damp time to visit. This rainfall is typically spread over 9 days, although this may vary considerably.

On the flip side this corresponds to an average of 9.8 hours of sunshine per day.

The data used in these monthly averages covers a period of over 100 years right up until last year. As such they are a valid prediction of what to expect for the weather in Joliet in August 2025.