Humidity Levels in Washington During September

The average humidity in September is listed below for places in Washington. 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 7 am and Afternoon measures are for 4 pm local standard time.

Average relative humidity (%) in September
Daily Place Morning Afternoon
78 Olympia 92 55
83 Quillayute 93 67
73 Seattle 86 57
54 Spokane 71 35
56 Yakima 71 32

Highest and Lowest Humidity

Below are the averages during September for maximum and minimum humidity levels in Washington. 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
92.9 4 am Olympia 55.1 4 pm
93.7 4 am Quillayute 66.3 1 pm
86.1 7 am Seattle 56.6 4 pm
70.9 4 am Spokane 34.6 4 pm
75.2 4 am Yakima 32.0 4 pm

World Data Center for Meteorology. Climate of the World.

Washington Humidity
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