September weather forecastVashon, WA
September
Weather in September
September, the first month of the autumn in Vashon, is also an agreeable month, with an average temperature ranging between max 70.3°F (21.3°C) and min 50.4°F (10.2°C).Temperature
The onset of September results in a small decrease in the average high-temperature, moderately receding from a moderately hot 77.7°F (25.4°C) in August to an agreeable 70.3°F (21.3°C). An average low-temperature of 50.4°F (10.2°C) marks the month of September.Humidity
The average relative humidity in September in Vashon is 74%.Rainfall
In September, the rain falls for 10.5 days. Throughout September, 0.91" (23mm) of precipitation is accumulated. In Vashon, during the entire year, the rain falls for 138.2 days and collects up to 14.09" (358mm) of precipitation.Snowfall
April through October are months without snowfall.Daylight
In Vashon, the average length of the day in September is 12h and 32min.On the first day of September, sunrise is at 6:29 am and sunset at 7:49 pm. On the last day of the month, sunrise is at 7:08 am and sunset at 6:50 pm PDT.
Sunshine
In Vashon, the average sunshine in September is 9.2h.UV index
The average daily maximum UV index in September is 4. A UV Index estimate of 3 to 5 represents a medium vulnerability from unprotected exposure to Sun's UV rays for ordinary individuals.Note: In September, the maximum UV index of 4 suggests these recommendations:
Undertake precautions - It is suggested to shield oneself from sunburn. The midday Sun can be harmful due to its potent UV radiation; seek shade and reduce exposure. For holistic sun protection encompassing the eyes, ears, face, and neck, a wide-brim hat is key.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Vashon, WA
- Average high temperature in September: 70.3°F
The warmest month (with the highest average high temperature) is August (77.7°F).
The month with the lowest average high temperature is December (43.5°F).
- Average low temperature in September: 50.4°F
The month with the highest average low temperature is August (53.6°F).
The coldest month (with the lowest average low temperature) is December (34.3°F).
Average pressure in September
Vashon, WA
- Average pressure in September: 30.01"Hg
The month with the highest atmospheric pressure is January (30.1"Hg).
The months with the lowest atmospheric pressure are March, August and September (30.01"Hg).
Average wind speed in September
Vashon, WA
- Average wind speed in September: 3.9mph
The windiest month (with the highest average wind speed) is March (5.3mph).
The calmest months (with the lowest average wind speed) are July and August (3.6mph).
Average humidity in September
Vashon, WA
- Average humidity in September: 74%
The months with the highest relative humidity are January and December (85%).
The month with the lowest relative humidity is July (68%).
Average rainfall in September
Vashon, WA
- Average rainfall in September: 0.91"
The wettest month (with the highest rainfall) is December (2.2").
The driest month (with the least rainfall) is July (0.31").
Average rainfall days in September
Vashon, WA
- Average rainfall days in September: 10.5 days
The month with the highest number of rainy days is April (14.9 days).
The month with the least rainy days is August (5.7 days).
Average snowfall in September
Vashon, WA
- Average snowfall in September: 0"
The month with the highest snowfall is February (2.52").
The months with the least snowfall are April, May, June, July, August, September and October (0").
Average snowfall days in September
Vashon, WA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is February (3.4 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
Vashon, WA
- Average daylight in September: 12h and 30min
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 12min
The month with the most sunshine is August (Average sunshine: 10h and 42min).
The month with the least sunshine is December (Average sunshine: 4h and 6min).
Average sunshine days in September
Vashon, WA
- Average sunshine days in September: 17.4 days
The month with the most sunshine days is August (22.8 days).
The month with the least sunshine days is February (13 days).
Average UV index in September
Vashon, WA
- Average UV index in September: 4
The months with the highest UV index are June, July and August (UV index 5).
The months with the lowest UV index are January, February, November and December (UV index 2).
Average cloud cover in September
Vashon, WA
- Average cloud cover in September: 35
The month with the most cloud cover is December (Cloud cover 58).
The month with the least cloud cover is August (Cloud cover 26).
Average visibility in September
Vashon, WA
- Average visibility in September: 6mi
The months with the highest visibility are May, June, July, August and September (6mi).
The months with the lowest visibility are January, February, March, April, October, November and December (5mi).
