September weather forecastHappy Valley, OR
September
Weather in September
The first month of the autumn, September, is also a moderately hot month in Happy Valley, Oregon, with temperature in the range of an average high of 74.1°F (23.4°C) and an average low of 51.1°F (10.6°C).Temperature
Happy Valley's September weather features a light decline in high-temperatures, reducing from a moderately hot 81.7°F (27.6°C) in August to a still warm 74.1°F (23.4°C). Significant dips from daytime highs mark the September nights, with a consistent average temperature of 51.1°F (10.6°C).Humidity
In Happy Valley, the average relative humidity in September is 69%.Rainfall
In Happy Valley, in September, it is raining for 10.4 days, with typically 1.69" (43mm) of accumulated precipitation. Throughout the year, there are 172.2 rainfall days, and 31.3" (795mm) of precipitation is accumulated.Snowfall
In Happy Valley, snow does not fall in April through October.Daylight
The average length of the day in September is 12h and 31min.On the first day of September in Happy Valley, sunrise is at 6:32 am and sunset at 7:47 pm. On the last day of the month, sunrise is at 7:08 am and sunset at 6:51 pm PDT.
Sunshine
In September, the average sunshine is 9.3h.UV index
In September, the average daily maximum UV index is 4. A UV Index estimate of 3 to 5 represents a medium health hazard from unprotected exposure to Sun's UV rays for ordinary individuals.Note: An average maximum UV index of 4 in September leads to these recommendations:
Make use of precautions - Suggestions to resist sunburn are communicated. Limiting sun exposure during midday hours helps in reducing the harmful effects of UV radiation. 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
Happy Valley, OR
- Average high temperature in September: 74.1°F
The warmest month (with the highest average high temperature) is August (81.7°F).
The month with the lowest average high temperature is December (44.4°F).
- Average low temperature in September: 51.1°F
The month with the highest average low temperature is August (54.5°F).
The coldest month (with the lowest average low temperature) is December (34.7°F).
Average pressure in September
Happy Valley, OR
- Average pressure in September: 30.01"Hg
The month with the highest atmospheric pressure is January (30.12"Hg).
The month with the lowest atmospheric pressure is August (30"Hg).
Average wind speed in September
Happy Valley, OR
- Average wind speed in September: 3.9mph
The windiest month (with the highest average wind speed) is January (6mph).
The calmest month (with the lowest average wind speed) is August (3.7mph).
Average humidity in September
Happy Valley, OR
- Average humidity in September: 69%
The month with the highest relative humidity is February (84%).
The month with the lowest relative humidity is August (63%).
Average rainfall in September
Happy Valley, OR
- Average rainfall in September: 1.69"
The wettest month (with the highest rainfall) is December (4.57").
The driest month (with the least rainfall) is July (0.31").
Average rainfall days in September
Happy Valley, OR
- Average rainfall days in September: 10.4 days
The month with the highest number of rainy days is March (20.4 days).
The month with the least rainy days is July (4.8 days).
Average snowfall in September
Happy Valley, OR
- Average snowfall in September: 0"
The month with the highest snowfall is March (1.46").
The months with the least snowfall are April, May, June, July, August, September and October (0").
Average snowfall days in September
Happy Valley, OR
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is February (2.3 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
Happy Valley, OR
- Average daylight in September: 12h and 30min
The month with the longest days is June (Average daylight: 15h and 36min).
The month with the shortest days is December (Average daylight: 8h and 48min).
- Average sunshine in September: 9h and 18min
The month with the most sunshine is August (Average sunshine: 11h and 0min).
The month with the least sunshine is February (Average sunshine: 4h and 12min).
Average sunshine days in September
Happy Valley, OR
- Average sunshine days in September: 17.5 days
The month with the most sunshine days is July (23.9 days).
The month with the least sunshine days is February (8.3 days).
Average UV index in September
Happy Valley, OR
- 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, November and December (UV index 2).
Average cloud cover in September
Happy Valley, OR
- Average cloud cover in September: 33
The month with the most cloud cover is February (Cloud cover 57).
The month with the least cloud cover is August (Cloud cover 22).
Average visibility in September
Happy Valley, OR
- Average visibility in September: 6mi
The months with the highest visibility are July, August, September and October (6mi).
The months with the lowest visibility are January, February, March, April, May, June, November and December (5mi).
