Contents
- Weather in December
- Frequently asked questions
- Average temperature in December
- Average pressure in December
- Average wind speed in December
- Average humidity in December
- Average rainfall in December
- Average rainfall days in December
- Average snowfall in December
- Average snowfall days in December
- Average daylight in December
- Average sunshine in December
- Average sunshine days in December
- Average UV index in December
- Average cloud cover in December
- Average visibility in December
Weather in December
Temperature
In Happy Valley, the lowest temperatures are generally noted in December, averaging a high of 44.4°F (6.9°C) and a low of 34.7°F (1.5°C).Humidity
In Happy Valley, the average relative humidity in December is 83%.Rainfall
December is the month with the most rainfall in Happy Valley. Rain falls for 18.5 days and accumulates 4.57" (116mm) of precipitation.Snowfall
January through March, November and December are months with snowfall. In Happy Valley, in December, during 0.8 snowfall days, 0.39" (10mm) of snow is typically accumulated. Throughout the year, there are 6.5 snowfall days, and 4.13" (105mm) of snow is accumulated.Daylight
December has the shortest days of the year, with an average of 8h and 48min of daylight.On the first day of December in Happy Valley, Oregon, sunrise is at 7:30 am and sunset at 4:28 pm. On the last day of the month, sunrise is at 7:49 am and sunset at 4:37 pm PST.
Sunshine
In December, the average sunshine is 4.4h.UV index
The months with the lowest UV index are January, February, November and December, with an average maximum UV index of 2. A UV Index estimate of 2, and below, represents a minimal health hazard from exposure to the Sun's UV rays for the average person.Note: In December, the maximum UV index of 2 suggests this advice:
Prolonged exposure to sunlight rarely troubles the majority, but constant protection is vital for babies, children, and fair-skinned people. Direct exposure to the Sun's intense radiation around midday should be avoided for health reasons. For optimum UV protection, wear sun-resistant attire complemented with a hat and quality shades. Caution! The reflection of snow can nearly double the intensity of the Sun's UV radiation.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What are the coldest months?
How cold is December?
What is the average humidity in December?
What is the wettest month?
How much does it rain in December?
How much does it snow in December?
What is the month with the shortest days?
What is the average length of the day in December?
When are sunrise and sunset in December?
How long on average sun shines in December?
What is the month with the lowest UV index?
How high is the UV index in December?
Average temperature in December
Happy Valley, OR
- Average high temperature in December: 44.4°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 December: 34.7°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 December
Happy Valley, OR
- Average pressure in December: 30.1"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 December
Happy Valley, OR
- Average wind speed in December: 5.7mph
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 December
Happy Valley, OR
- Average humidity in December: 83%
The month with the highest relative humidity is February (84%).
The month with the lowest relative humidity is August (63%).
Average rainfall in December
Happy Valley, OR
- Average rainfall in December: 4.57"
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 December
Happy Valley, OR
- Average rainfall days in December: 18.5 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 December
Happy Valley, OR
- Average snowfall in December: 0.39"
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 December
Happy Valley, OR
- Average snowfall days in December: 0.8 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 December /
Average sunshine in December
Happy Valley, OR
- Average daylight in December: 8h and 5min
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 December: 4h 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 December
Happy Valley, OR
- Average sunshine days in December: 10.9 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 December
Happy Valley, OR
- Average UV index in December: 2
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 December
Happy Valley, OR
- Average cloud cover in December: 55
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 December
Happy Valley, OR
- Average visibility in December: 5mi
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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