Contents
- Weather in September
- Frequently asked questions
- Average temperature in September
- Average pressure in September
- Average wind speed in September
- Average humidity in September
- Average rainfall in September
- Average rainfall days in September
- Average snowfall in September
- Average snowfall days in September
- Average daylight in September
- Average sunshine in September
- Average sunshine days in September
- Average UV index in September
- Average cloud cover in September
- Average visibility in September
Weather in September
Temperature
As August transitions into September, Clayton sees a drop in the average high-temperature, transitioning from a warm 84°F (28.9°C) to a pleasant 72.7°F (22.6°C). Clayton sees a large disparity in day to night temperatures in September, with the night temperature dropping to an average of 46.6°F (8.1°C).Humidity
In September, the average relative humidity is 53%.Rainfall
In Clayton, in September, it is raining for 7 days, with typically 0.63" (16mm) of accumulated precipitation. In Clayton, during the entire year, the rain falls for 124.9 days and collects up to 17.44" (443mm) of precipitation.Snowfall
Months with snowfall are January through May, September through December. September is the first month it typically snows. Throughout September, in the average 0.2 snowfall days, it receives 0.51" (13mm) of snow. In Clayton, during the entire year, snow falls for 69.2 days and aggregates up to 42.99" (1092mm) of snow.Daylight
In September, the average length of the day is 12h and 33min.On the first day of September, sunrise is at 6:09 am and sunset at 7:30 pm. On the last day of the month, sunrise is at 6:49 am and sunset at 6:30 pm PDT.
Sunshine
In Clayton, the average sunshine in September is 10.1h.UV index
The average daily maximum UV index in September is 4. A UV Index value of 3 to 5 symbolizes a medium health hazard from exposure to the Sun's UV rays for average individuals.Note: During September, 4 as the daily maximum UV index converts into the following advice:
Ensure safety - Recommendations to avert sunburn are presented. The Sun's harshest UV rays are around midday; it's wise to seek shade and limit time outdoors. Counter UV radiation's ill effects with clothing designed for sun safety and UV-resistant eyewear. Be mindful! The reflection from snow can increase the Sun's UV radiation nearly twice.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the average September temperature?
What is the average humidity in September?
How much does it rain in September?
When does it start to snow?
How many hours of daylight does Clayton have in September?
When is the sunrise / sunset in September?
How long on average sun shines in September?
What is the UV index intensity in September?
Average temperature in September
Clayton, WA
- Average high temperature in September: 72.7°F
The warmest month (with the highest average high temperature) is August (84°F).
The month with the lowest average high temperature is December (31.3°F).
- Average low temperature in September: 46.6°F
The month with the highest average low temperature is August (54.3°F).
The coldest month (with the lowest average low temperature) is December (20.3°F).
Average pressure in September
Clayton, WA
- Average pressure in September: 29.96"Hg
The month with the highest atmospheric pressure is January (30.19"Hg).
The months with the lowest atmospheric pressure are June and August (29.91"Hg).
Average wind speed in September
Clayton, WA
- Average wind speed in September: 4.7mph
The windiest month (with the highest average wind speed) is April (5.6mph).
The calmest month (with the lowest average wind speed) is December (4mph).
Average humidity in September
Clayton, WA
- Average humidity in September: 53%
The month with the highest relative humidity is January (92%).
The month with the lowest relative humidity is August (43%).
Average rainfall in September
Clayton, WA
- Average rainfall in September: 0.63"
The wettest month (with the highest rainfall) is January (2.4").
The driest month (with the least rainfall) is August (0.31").
Average rainfall days in September
Clayton, WA
- Average rainfall days in September: 7 days
The month with the highest number of rainy days is March (16.2 days).
The month with the least rainy days is August (5.1 days).
Average snowfall in September
Clayton, WA
- Average snowfall in September: 0.51"
The month with the highest snowfall is January (13.23").
The months with the least snowfall are June, July and August (0").
Average snowfall days in September
Clayton, WA
- Average snowfall days in September: 0.2 days
The month with the highest number of snowfall days is December (16.9 days).
The months with the least snowfall days are June, July and August (0 days).
Average daylight in September /
Average sunshine in September
Clayton, WA
- Average daylight in September: 12h and 4min
The month with the longest days is June (Average daylight: 16h and 0min).
The month with the shortest days is December (Average daylight: 8h and 30min).
- Average sunshine in September: 10h and 1min
The month with the most sunshine is August (Average sunshine: 12h and 0min).
The month with the least sunshine is January (Average sunshine: 3h and 24min).
Average sunshine days in September
Clayton, WA
- Average sunshine days in September: 21.3 days
The month with the most sunshine days is July (24.2 days).
The month with the least sunshine days is March (9.7 days).
Average UV index in September
Clayton, WA
- Average UV index in September: 4
The month with the highest UV index is July (UV index 6).
The months with the lowest UV index are February, November and December (UV index 1).
Average cloud cover in September
Clayton, WA
- Average cloud cover in September: 22
The month with the most cloud cover is January (Cloud cover 64).
The month with the least cloud cover is August (Cloud cover 13).
Average visibility in September
Clayton, WA
- Average visibility in September: 6mi
The months with the highest visibility are April, May, June, July, August, September and October (6mi).
The month with the lowest visibility is January (3mi).
Clayton, Washington, USA
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