DeKalb (IL) Weather & Climate: Best Time to Visit

In DeKalb, temperatures differ significantly between summer and winter months. Average daytime temperatures reach a comfortable 28°C (82°F) in July. In January, the coolest month of the year, temperatures drop to a very cold -2°C (28°F).

At night, temperatures range from around 17°C (63°F) in July to -11°C (12°F) in January.

Check out our detailed temperature page for more information.

Temperature ranges by month

On average, DeKalb receives a reasonable amount of rain/snowfall, with an annual precipitation of 985 mm (39 in). DeKalb can be quite wet during June, receiving approximately 127 mm (5 in) of precipitation over 14 rainy days.

In contrast, during the driest month (January), you will experience much drier conditions, with 38 mm (1.5 in) of precipitation spread across 10 snowy days. For more details, please visit our DeKalb Precipitation page.

The mean monthly precipitation over the year, including rain, hail, and snow

The average number of days each month with precipitation

DeKalb can be enjoyed more throughout the sunniest month of July under a blue sky, with approximately 10.6 hours of sunshine daily. In contrast, the city experiences much darker days in December, with only 3.6 hours of sunlight per day.

Visit our detailed sunshine hours page for more information.

Monthly hours of sunshine

Daily hours of sunshine

Daily percentage of sunshine

The relative humidity is high throughout the year in DeKalb.

The city experiences its highest humidity in December, reaching 76%. In May, the humidity drops to its lowest level at 64%. What does this mean? Read our detailed page on humidity levels for further details.

Relative humidity over the year