Humidity Levels in Illinois During September

The average humidity in September is listed below for places in Illinois. The tables give daily averages along with highest and lowest relative humidity levels.

Relative humidity measures the actual amount of moisture in the air as a percentage of the maximum amount of moisture the air can hold.

All the numbers here are averages for the years 1961 to 1990.

Average Humidity

In this table, the Daily number is the average of humidity readings taken every three hours throughout the day. Morning percentages are for 6 am and Afternoon measures are for 3 pm local standard time.

Average relative humidity (%) in September
Daily Place Morning Afternoon
71 Chicago 85 55
73 Moline 88 53
73 Peoria 88 54
74 Rockford 90 54
72 Springfield 88 52

Highest and Lowest Humidity

Below are the averages during September for maximum and minimum humidity levels in Illinois. The hours when this month's highest and lowest humidity readings usually occur are given in local standard time.

Daily high and low relative humidity (%) averages in September
High Time Place Low Time
85.2 6 am Chicago 54.6 3 pm
87.5 6 am Moline 53.4 3 pm
87.9 6 am Peoria 54.0 3 pm
89.8 6 am Rockford 54.2 3 pm
88.4 6 am Springfield 51.9 3 pm

World Data Center for Meteorology. Climate of the World.

Illinois Humidity
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