September weather forecastUmtanum, WA
September
Weather in September
September, the first month of the autumn in Umtanum, is still a pleasant month, with an average temperature ranging between min 49.1°F (9.5°C) and max 71.1°F (21.7°C).Temperature
Setting in of September comes with a decrease in the average high-temperature, moving from a moderately hot 82°F (27.8°C) in August to an agreeable 71.1°F (21.7°C). A sharp contrast between day and night is prevalent in September with an average nighttime temperature of 49.1°F (9.5°C) in Umtanum.Humidity
In Umtanum, the average relative humidity in September is 54%.Rainfall
In Umtanum, Washington, during September, the rain falls for 6.1 days and regularly aggregates up to 0.47" (12mm) of precipitation. Throughout the year, there are 99.9 rainfall days, and 8.66" (220mm) of precipitation is accumulated.Snowfall
Months with snowfall in Umtanum, Washington, are January through April, September through December. September is the first month it typically snows. Throughout September, in the average 0.3 snowfall days, it receives 0.31" (8mm) of snow. Throughout the year, in Umtanum, there are 35.4 snowfall days, and 15.59" (396mm) of snow is accumulated.Daylight
The average length of the day in September in Umtanum is 12h and 32min.On the first day of September in Umtanum, sunrise is at 6:22 am and sunset at 7:40 pm. On the last day of the month, sunrise is at 7:00 am and sunset at 6:42 pm PDT.
Sunshine
The average sunshine in September is 10.7h.UV index
In September, the average daily maximum UV index is 4. A UV Index reading of 3 to 5 represents a medium health hazard from exposure to the Sun's UV radiation for the average person.Note: In September, a daily UV index of 4 turns into the following recommendations:
Guard yourself - Avoiding sunburn is suggested. Minimize direct exposure to the Sun during midday when its radiation is at its peak. Select sunglasses that boast both UVA and UVB protection to limit the adverse effects of the sun on the eyes. Warning! The reflection from snow can nearly magnify the Sun's UV radiation twofold.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Umtanum, WA
- Average high temperature in September: 71.1°F
The warmest months (with the highest average high temperature) are July and August (82°F).
The month with the lowest average high temperature is December (33.3°F).
- Average low temperature in September: 49.1°F
The month with the highest average low temperature is August (55.2°F).
The coldest month (with the lowest average low temperature) is December (21.4°F).
Average pressure in September
Umtanum, WA
- Average pressure in September: 29.97"Hg
The month with the highest atmospheric pressure is January (30.15"Hg).
The month with the lowest atmospheric pressure is August (29.94"Hg).
Average wind speed in September
Umtanum, WA
- Average wind speed in September: 6.9mph
The windiest month (with the highest average wind speed) is June (8.9mph).
The calmest month (with the lowest average wind speed) is December (4.2mph).
Average humidity in September
Umtanum, WA
- Average humidity in September: 54%
The month with the highest relative humidity is January (87%).
The months with the lowest relative humidity are July and August (46%).
Average rainfall in September
Umtanum, WA
- Average rainfall in September: 0.47"
The wettest month (with the highest rainfall) is December (1.3").
The driest month (with the least rainfall) is July (0.16").
Average rainfall days in September
Umtanum, WA
- Average rainfall days in September: 6.1 days
The month with the highest number of rainy days is March (12.4 days).
The month with the least rainy days is August (2.8 days).
Average snowfall in September
Umtanum, WA
- Average snowfall in September: 0.31"
The month with the highest snowfall is December (4.65").
The months with the least snowfall are May, June, July and August (0").
Average snowfall days in September
Umtanum, WA
- Average snowfall days in September: 0.3 days
The months with the highest number of snowfall days are January and December (8.7 days).
The months with the least snowfall days are May, June, July and August (0 days).
Average daylight in September /
Average sunshine in September
Umtanum, 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: 10h and 42min
The months with the most sunshine are July and August (Average sunshine: 12h and 0min).
The months with the least sunshine are January and December (Average sunshine: 4h and 48min).
Average sunshine days in September
Umtanum, WA
- Average sunshine days in September: 22.8 days
The month with the most sunshine days is July (27.1 days).
The month with the least sunshine days is February (13.5 days).
Average UV index in September
Umtanum, 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 January, February, March, November and December (UV index 2).
Average cloud cover in September
Umtanum, WA
- Average cloud cover in September: 18
The month with the most cloud cover is January (Cloud cover 48).
The months with the least cloud cover are July and August (Cloud cover 11).
Average visibility in September
Umtanum, WA
- Average visibility in September: 6mi
The months with the highest visibility are March, April, May, June, July, August, September, October and November (6mi).
The months with the lowest visibility are January and December (4mi).
