Humidity Levels in Iowa During September

The average humidity in September is listed below for places in Iowa. 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 Des Moines 85 54
Dubuque 87 59
71 Sioux City 86 53
74 Waterloo 89 55

Highest and Lowest Humidity

Below are the averages during September for maximum and minimum humidity levels in Iowa. 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
84.9 6 am Des Moines 54.1 3 pm
87.1 6 am Dubuque 58.8 3 pm
86.2 6 am Sioux City 52.6 3 pm
88.9 6 am Waterloo 54.7 3 pm

World Data Center for Meteorology. Climate of the World.

Iowa Humidity
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