Contents
- Weather in September
- Frequently asked questions
- Average temperature in September
- Average pressure in September
- Average wind speed in September
- Average humidity in September
- Average rainfall in September
- Average rainfall days in September
- Average snowfall in September
- Average snowfall days in September
- Average daylight in September
- Average sunshine in September
- Average sunshine days in September
- Average UV index in September
- Average cloud cover in September
- Average visibility in September
Weather in September
Temperature
The move into September indicates a slight reduction in the average high-temperature, down from August's moderately hot 81.7°F (27.6°C) to a still warm 74.1°F (23.4°C). Throughout the month of September, Happy Valley observes a dramatic downturn from the daytime peak temperatures, expecting an average low of 51.1°F (10.6°C).Humidity
The average relative humidity in September in Happy Valley is 69%.Rainfall
In Happy Valley, in September, during 10.4 rainfall days, 1.69" (43mm) of precipitation is typically accumulated. In Happy Valley, Oregon, during the entire year, the rain falls for 172.2 days and collects up to 31.3" (795mm) of precipitation.Snowfall
In Happy Valley, snow does not fall in April through October.Daylight
In September, the average length of the day in Happy Valley is 12h and 31min.On the first day of September in Happy Valley, Oregon, 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 in Happy Valley is 9.3h.UV index
In September, the average daily maximum UV index in Happy Valley is 4. A UV Index reading of 3 to 5 represents a moderate health risk from exposure to the Sun's UV rays for average individuals.Note: The UV index of 4 during September translates into the following guidance:
Take precautions - Protection against skin and eye damage is obliged. Midday is the peak time for the Sun's radiation; stay in the shade and protect yourself. Sunglasses providing both UVA and UVB protection are non-negotiable on sunlit days.
Frequently asked questions
What are the temperatures in Happy Valley in September?
What is the average humidity in September in Happy Valley?
How many days does it rain in September in Happy Valley?
When it does not snow in Happy Valley?
How many hours of daylight does Happy Valley have in September?
What time are sunrise and sunset in September in Happy Valley?
How long on average sun shines in September in Happy Valley?
What is the UV index intensity in September in Happy Valley?
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 3min
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 2min
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).
Happy Valley, Oregon, USA
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