September weather forecastBrier, WA
September
Weather in September
September, the first month of the autumn in Brier, is still a comfortable month, with an average temperature varying between 51.6°F (10.9°C) and 67.6°F (19.8°C).Temperature
The beginning of September subtly marks a decrease in the average high-temperature, transitioning from a warm 73.9°F (23.3°C) in August to a refreshing 67.6°F (19.8°C). An average temperature of 51.6°F (10.9°C) marks the nights in September.Humidity
In September, the average relative humidity is 76%.Rainfall
In Brier, in September, during 11.9 rainfall days, 1.42" (36mm) of precipitation is typically accumulated. Throughout the year, in Brier, there are 173 rainfall days, and 25" (635mm) of precipitation is accumulated.Snowfall
In Brier, snow does not fall in May through October.Daylight
In Brier, the average length of the day in September is 12h and 33min.On the first day of September, sunrise is at 6:28 am and sunset at 7:49 pm. On the last day of the month, sunrise is at 7:08 am and sunset at 6:49 pm PDT.
Sunshine
The average sunshine in September is 9.5h.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 rays for the average person.Note: In September, a daily maximum UV index of 4 leads to the following instructions:
Act with care - The suggestion to avoid sunburn is emphasized. Considering the Sun's intensity during midday, it's wise to minimize direct exposure. Employ a wide-brim hat for potent defense against up to 50% of UV rays.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Brier, WA
- Average high temperature in September: 67.6°F
The warmest month (with the highest average high temperature) is August (73.9°F).
The month with the lowest average high temperature is December (43.3°F).
- Average low temperature in September: 51.6°F
The month with the highest average low temperature is August (54.1°F).
The coldest month (with the lowest average low temperature) is December (35.8°F).
Average pressure in September
Brier, WA
- Average pressure in September: 30.01"Hg
The month with the highest atmospheric pressure is January (30.09"Hg).
The months with the lowest atmospheric pressure are March, August and September (30.01"Hg).
Average wind speed in September
Brier, WA
- Average wind speed in September: 4mph
The windiest month (with the highest average wind speed) is November (5.9mph).
The calmest month (with the lowest average wind speed) is August (3.5mph).
Average humidity in September
Brier, WA
- Average humidity in September: 76%
The months with the highest relative humidity are January, February and December (84%).
The month with the lowest relative humidity is July (72%).
Average rainfall in September
Brier, WA
- Average rainfall in September: 1.42"
The wettest month (with the highest rainfall) is December (3.5").
The driest month (with the least rainfall) is July (0.39").
Average rainfall days in September
Brier, WA
- Average rainfall days in September: 11.9 days
The month with the highest number of rainy days is March (19.8 days).
The month with the least rainy days is August (6.8 days).
Average snowfall in September
Brier, WA
- Average snowfall in September: 0"
The month with the highest snowfall is February (3.58").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in September
Brier, WA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is February (4.7 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
Brier, 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 30min
The month with the most sunshine is August (Average sunshine: 10h and 48min).
The month with the least sunshine is January (Average sunshine: 4h and 30min).
Average sunshine days in September
Brier, WA
- Average sunshine days in September: 15.9 days
The month with the most sunshine days is August (22.5 days).
The month with the least sunshine days is November (9.2 days).
Average UV index in September
Brier, 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
Brier, WA
- Average cloud cover in September: 32
The months with the most cloud cover are January and December (Cloud cover 53).
The month with the least cloud cover is August (Cloud cover 25).
Average visibility in September
Brier, WA
- Average visibility in September: 6mi
The months with the highest visibility are February, March, April, May, June, July, August, September, October, November and December (6mi).
The month with the lowest visibility is January (5mi).





