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
With September's onset, the weather reveals a slight temperature decrease, transitioning from a warm 76.6°F (24.8°C) in August to an agreeable 68.9°F (20.5°C). During September, an average low-temperature of 47.5°F (8.6°C) is observed.Humidity
In Union, Washington, the average relative humidity in September is 78%.Rainfall
In Union, during September, the rain falls for 12.3 days and regularly aggregates up to 1.85" (47mm) of precipitation. In Union, during the entire year, the rain falls for 185.4 days and collects up to 42.87" (1089mm) of precipitation.Snowfall
April through October are months without snowfall.Daylight
In September, the average length of the day in Union is 12h and 32min.On the first day of the month, sunrise is at 6:32 am and sunset at 7:51 pm. On the last day of September, sunrise is at 7:11 am and sunset at 6:53 pm PDT.
Sunshine
In Union, Washington, the average sunshine in September is 9h.UV index
In Union, the average daily maximum UV index in September is 3. A UV Index reading of 3 to 5 represents a medium health hazard from unprotected exposure to Sun's UV rays for the ordinary person.Note: In September, the average maximum UV index of 3 translates into the following recommendations:
Make use of precautions - Suggestions to resist sunburn are communicated. Midday Sun has the strongest UV rays, making it crucial to limit exposure and find shade. Experience reduced UV exposure by about half when donning a wide-brim hat.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What are September temperatures in Union?
What is the average humidity in September in Union?
How many days does it rain in September in Union?
When it does not snow in Union?
How many hours of daylight does Union have in September?
What time are sunrise and sunset in September in Union?
How long on average sun shines in September in Union?
How high is the UV index in September in Union?
Average temperature in September
Union, WA
- Average high temperature in September: 68.9°F
The warmest month (with the highest average high temperature) is August (76.6°F).
The month with the lowest average high temperature is December (41.5°F).
- Average low temperature in September: 47.5°F
The month with the highest average low temperature is August (50.4°F).
The coldest month (with the lowest average low temperature) is February (32.7°F).
Average pressure in September
Union, WA
- Average pressure in September: 30.02"Hg
The month with the highest atmospheric pressure is January (30.08"Hg).
The month with the lowest atmospheric pressure is March (30.01"Hg).
Average wind speed in September
Union, WA
- Average wind speed in September: 3.4mph
The windiest month (with the highest average wind speed) is March (4.3mph).
The calmest month (with the lowest average wind speed) is September (3.4mph).
Average humidity in September
Union, WA
- Average humidity in September: 78%
The months with the highest relative humidity are November and December (90%).
The month with the lowest relative humidity is July (72%).
Average rainfall in September
Union, WA
- Average rainfall in September: 1.85"
The wettest month (with the highest rainfall) is January (7.24").
The driest month (with the least rainfall) is July (0.43").
Average rainfall days in September
Union, WA
- Average rainfall days in September: 12.3 days
The month with the highest number of rainy days is March (21.4 days).
The month with the least rainy days is August (6.3 days).
Average snowfall in September
Union, WA
- Average snowfall in September: 0"
The month with the highest snowfall is February (2.17").
The months with the least snowfall are April, May, June, July, August, September and October (0").
Average snowfall days in September
Union, WA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is February (3.3 days).
The months with the least snowfall days are May, June, July, August, September and October (0 days).
Average daylight in September /
Average sunshine in September
Union, WA
- Average daylight in September: 12h and 3min
The month with the longest days is June (Average daylight: 15h and 54min).
The month with the shortest days is December (Average daylight: 8h and 30min).
- Average sunshine in September: 9h and 0min
The month with the most sunshine is August (Average sunshine: 10h and 42min).
The month with the least sunshine is December (Average sunshine: 3h and 30min).
Average sunshine days in September
Union, WA
- Average sunshine days in September: 15.1 days
The month with the most sunshine days is July (21.7 days).
The month with the least sunshine days is March (7.5 days).
Average UV index in September
Union, WA
- Average UV index in September: 3
The months with the highest UV index are June and July (UV index 5).
The months with the lowest UV index are January, February, November and December (UV index 2).
Average cloud cover in September
Union, WA
- Average cloud cover in September: 39
The months with the most cloud cover are January and December (Cloud cover 64).
The months with the least cloud cover are July and August (Cloud cover 30).
Average visibility in September
Union, WA
- Average visibility in September: 5mi
The months with the highest visibility are June, July, August and September (5mi).
The months with the lowest visibility are January, February, March, April, May, October, November and December (4mi).
Union, Washington, USA
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