September weather forecastOlympia, WA
September
Weather in September
September in Olympia signals the onset of fall, with a decrease in temperature and a gradual increase in rainfall. Despite the month witnessing increased rain, 1.81" (46mm), the outdoors remains pleasant. This is the perfect month to take leisurely walks and experience the changing foliage around the city. A progressive drop in temperature brings cooler nights, hinting at the approaching winter.Moving into October, the weather conditions continue the downward trend in temperature.Temperature
In September, the meteorological conditions in Olympia, Washington, change slightly, with the average high-temperature moving from a moderately hot 78.6°F (25.9°C) in August to an agreeable 70.5°F (21.4°C). Olympia's September nights cool down significantly from the day's heat, to an average low-temperature of 47.7°F (8.7°C).Humidity
In Olympia, Washington, the average relative humidity in September is 78%.Rainfall
In Olympia, Washington, in September, during 11.7 rainfall days, 1.81" (46mm) of precipitation is typically accumulated. Throughout the year, in Olympia, there are 177.4 rainfall days, and 37.05" (941mm) of precipitation is accumulated.Snowfall
In Olympia, snow does not fall in April through October.Daylight
In Olympia, Washington, the average length of the day in September is 12h and 32min.On the first day of the month, sunrise is at 6:32 am and sunset at 7:50 pm. On the last day of September, sunrise is at 7:10 am and sunset at 6:52 pm PDT.
Sunshine
The average sunshine in September in Olympia is 8.3h.UV index
The average daily maximum UV index in September is 4. A UV Index estimate of 3 to 5 represents a moderate threat to health from exposure to the Sun's UV radiation for average individuals.Note: A maximum daily UV index of 4 during September morphs into the following directions:
Undertake protective steps - Recommendations to avoid sunburn are issued. Avoiding the Sun during its peak radiation time around midday is a healthy practice. Always opt for UVA and UVB-resistant sunglasses on radiant days.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Olympia, WA
- Average high temperature in September: 70.5°F
The warmest month (with the highest average high temperature) is August (78.6°F).
The month with the lowest average high temperature is December (43°F).
- Average low temperature in September: 47.7°F
The month with the highest average low temperature is August (50.5°F).
The coldest month (with the lowest average low temperature) is December (33.4°F).
Average pressure in September
Olympia, WA
- Average pressure in September: 30.02"Hg
The month with the highest atmospheric pressure is January (30.09"Hg).
The month with the lowest atmospheric pressure is March (30.01"Hg).
Average wind speed in September
Olympia, WA
- Average wind speed in September: 3.8mph
The windiest months (with the highest average wind speed) are March and November (4.6mph).
The calmest month (with the lowest average wind speed) is September (3.8mph).
Average humidity in September
Olympia, WA
- Average humidity in September: 78%
The months with the highest relative humidity are January, November and December (89%).
The month with the lowest relative humidity is July (71%).
Average rainfall in September
Olympia, WA
- Average rainfall in September: 1.81"
The wettest month (with the highest rainfall) is December (5.79").
The driest month (with the least rainfall) is July (0.39").
Average rainfall days in September
Olympia, WA
- Average rainfall days in September: 11.7 days
The month with the highest number of rainy days is March (20.4 days).
The month with the least rainy days is August (5.5 days).
Average snowfall in September
Olympia, WA
- Average snowfall in September: 0"
The month with the highest snowfall is February (2.32").
The months with the least snowfall are April, May, June, July, August, September and October (0").
Average snowfall days in September
Olympia, 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
Olympia, WA
- Average daylight in September: 12h and 30min
The month with the longest days is June (Average daylight: 15h and 48min).
The month with the shortest days is December (Average daylight: 8h and 36min).
- Average sunshine in September: 8h and 18min
The month with the most sunshine is August (Average sunshine: 10h and 12min).
The month with the least sunshine is December (Average sunshine: 3h and 24min).
Average sunshine days in September
Olympia, WA
- Average sunshine days in September: 16.1 days
The month with the most sunshine days is August (22.4 days).
The month with the least sunshine days is February (8.4 days).
Average UV index in September
Olympia, WA
- Average UV index in September: 4
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
Olympia, WA
- Average cloud cover in September: 45
The months with the most cloud cover are January and December (Cloud cover 65).
The months with the least cloud cover are July and August (Cloud cover 35).
Average visibility in September
Olympia, WA
- Average visibility in September: 4mi
The months with the highest visibility are June, July and August (5mi).
The months with the lowest visibility are January, February, March, April, May, September, October, November and December (4mi).
