September weather forecastUmatilla, OR
September
Weather in September
The first month of the autumn, September, is still a warm month in Umatilla, Oregon, with an average temperature fluctuating between 77.2°F (25.1°C) and 57.4°F (14.1°C).Temperature
During the transition into September, Umatilla observes a decrease in the average high-temperature, falling from a hot 87.8°F (31°C) in August to a warm 77.2°F (25.1°C). Throughout September, Umatilla experiences a low-temperature average of 57.4°F (14.1°C).Humidity
In Umatilla, the average relative humidity in September is 44%.Rainfall
In September, the rain falls for 5.6 days. Throughout September, 0.31" (8mm) of precipitation is accumulated. In Umatilla, during the entire year, the rain falls for 106.1 days and collects up to 7.76" (197mm) of precipitation.Snowfall
January through March, September, November and December are months with snowfall. September is the first month it typically snows. Throughout September, in the average 0.1 snowfall days, it receives 0.04" (1mm) of snow. In Umatilla, Oregon, during the entire year, snow falls for 10.3 days and aggregates up to 6.02" (153mm) of snow.Daylight
In September, the average length of the day is 12h and 31min.On the first day of September, sunrise is at 6:19 am and sunset at 7:34 pm. On the last day of the month, sunrise is at 6:55 am and sunset at 6:38 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 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:
Make use of precautions - Suggestions to resist sunburn are communicated. When the Sun's UV radiation is most intense during midday, it's best to find shade and limit exposure. Select sunglasses that boast both UVA and UVB protection to limit the adverse effects of the sun on the eyes. Foresee this! The reflection from snow can nearly double the intensity of UV radiation from the Sun.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Umatilla, OR
- Average high temperature in September: 77.2°F
The warmest month (with the highest average high temperature) is July (89.1°F).
The month with the lowest average high temperature is December (38.7°F).
- Average low temperature in September: 57.4°F
The month with the highest average low temperature is August (64.2°F).
The coldest month (with the lowest average low temperature) is December (28.6°F).
Average pressure in September
Umatilla, OR
- Average pressure in September: 29.96"Hg
The month with the highest atmospheric pressure is January (30.19"Hg).
The month with the lowest atmospheric pressure is August (29.91"Hg).
Average wind speed in September
Umatilla, OR
- Average wind speed in September: 7.2mph
The windiest month (with the highest average wind speed) is April (9.3mph).
The calmest month (with the lowest average wind speed) is December (6.2mph).
Average humidity in September
Umatilla, OR
- Average humidity in September: 44%
The month with the highest relative humidity is January (79%).
The months with the lowest relative humidity are July and August (36%).
Average rainfall in September
Umatilla, OR
- Average rainfall in September: 0.31"
The wettest month (with the highest rainfall) is March (1.02").
The driest month (with the least rainfall) is July (0.16").
Average rainfall days in September
Umatilla, OR
- Average rainfall days in September: 5.6 days
The month with the highest number of rainy days is March (13.1 days).
The month with the least rainy days is July (3.8 days).
Average snowfall in September
Umatilla, OR
- Average snowfall in September: 0.04"
The month with the highest snowfall is February (2.83").
The months with the least snowfall are April, May, June, July, August and October (0").
Average snowfall days in September
Umatilla, OR
- Average snowfall days in September: 0.1 days
The month with the highest number of snowfall days is December (3.2 days).
The months with the least snowfall days are April, May, June, July, August and October (0 days).
Average daylight in September /
Average sunshine in September
Umatilla, OR
- Average daylight in September: 12h and 30min
The month with the longest days is June (Average daylight: 15h and 42min).
The month with the shortest days is December (Average daylight: 8h and 42min).
- 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: 5h and 24min).
Average sunshine days in September
Umatilla, OR
- Average sunshine days in September: 22.6 days
The month with the most sunshine days is July (25.3 days).
The month with the least sunshine days is February (14 days).
Average UV index in September
Umatilla, OR
- Average UV index in September: 4
The month with the highest UV index is July (UV index 7).
The months with the lowest UV index are January, February, November and December (UV index 2).
Average cloud cover in September
Umatilla, OR
- Average cloud cover in September: 16
The months with the most cloud cover are January and December (Cloud cover 44).
The month with the least cloud cover is July (Cloud cover 9).
Average visibility in September
Umatilla, OR
- Average visibility in September: 6mi
The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
