December weather forecastTri-City, OR
December
Weather in December
December, the first month of the winter in Tri-City, is also a frosty month, with an average temperature varying between 32.2°F (0.1°C) and 45.7°F (7.6°C).Temperature
The month of December, characterized by an average high of 45.7°F (7.6°C) and a low of 32.2°F (0.1°C), is recognized as the coldest.Humidity
January, February and December, with an average relative humidity of 86%, are the most humid months.Rainfall
The wettest months are January, February and December, with an average 1.1" (28mm) of rainfall.Snowfall
January through March, November and December are months with snowfall. In Tri-City, Oregon, in December, during 0.5 snowfall days, 0.31" (8mm) of snow is typically accumulated. Throughout the year, in Tri-City, there are 3.5 snowfall days, and 2.2" (56mm) of snow is accumulated.Daylight
The month with the shortest days is December, with an average of 9h and 6min of daylight.On the first day of December, sunrise is at 7:25 am and sunset at 4:39 pm. On the last day of the month, sunrise is at 7:44 am and sunset at 4:48 pm PST.
Sunshine
With an average of 4.3h of sunshine, December has the least sunshine of the year.UV index
January, February, November and December, with an average maximum UV index of 2, are months with the lowest UV index. A UV Index reading of 2, and below, represents a minimal health vulnerability from exposure to the Sun's UV rays for average individuals.Note: In December, the maximum UV index of 2 transforms into these recommendations:
While most people are not greatly affected by extended sun exposure, those with fair skin, babies, and children must always have protection. Solar radiation peaks around mid-day, so it's wise to limit exposure to the Sun at this time. Sun-protective clothing, a long-sleeved shirt and pants, a wide-brimmed hat, and UVA and UVB-blocking sunglasses are particularly helpful in blocking UV radiation's harmful effects. Keep in mind! Snow's reflective quality 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
Average temperature in December
Tri-City, OR
- Average high temperature in December: 45.7°F
The warmest month (with the highest average high temperature) is August (81.1°F).
The month with the lowest average high temperature is December (45.7°F).
- Average low temperature in December: 32.2°F
The month with the highest average low temperature is August (47.7°F).
The coldest month (with the lowest average low temperature) is December (32.2°F).
Average pressure in December
Tri-City, OR
- Average pressure in December: 30.11"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
Tri-City, OR
- Average wind speed in December: 3.9mph
The windiest month (with the highest average wind speed) is January (4.1mph).
The calmest month (with the lowest average wind speed) is September (3.2mph).
Average humidity in December
Tri-City, OR
- Average humidity in December: 86%
The months with the highest relative humidity are January, February and December (86%).
The month with the lowest relative humidity is August (69%).
Average rainfall in December
Tri-City, OR
- Average rainfall in December: 1.1"
The wettest months (with the highest rainfall) are January, February and December (1.1").
The driest months (with the least rainfall) are July and August (0.16").
Average rainfall days in December
Tri-City, OR
- Average rainfall days in December: 11.4 days
The month with the highest number of rainy days is March (12.6 days).
The month with the least rainy days is August (2.4 days).
Average snowfall in December
Tri-City, OR
- Average snowfall in December: 0.31"
The month with the highest snowfall is February (0.87").
The months with the least snowfall are April, May, June, July, August, September and October (0").
Average snowfall days in December
Tri-City, OR
- Average snowfall days in December: 0.5 days
The month with the highest number of snowfall days is February (1.5 days).
The months with the least snowfall days are April, May, June, July, August, September and October (0 days).
Average daylight in December /
Average sunshine in December
Tri-City, OR
- Average daylight in December: 9h and 6min
The month with the longest days is June (Average daylight: 15h and 18min).
The month with the shortest days is December (Average daylight: 9h and 6min).
- Average sunshine in December: 4h and 18min
The month with the most sunshine is August (Average sunshine: 11h and 18min).
The month with the least sunshine is December (Average sunshine: 4h and 18min).
Average sunshine days in December
Tri-City, OR
- Average sunshine days in December: 17.7 days
The month with the most sunshine days is August (26.5 days).
The month with the least sunshine days is March (16.1 days).
Average UV index in December
Tri-City, 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
Tri-City, OR
- Average cloud cover in December: 56
The month with the most cloud cover is March (Cloud cover 60).
The month with the least cloud cover is August (Cloud cover 25).
Average visibility in December
Tri-City, OR
- Average visibility in December: 4mi
The months with the highest visibility are July, August and September (5mi).
The months with the lowest visibility are January, February, March, April, May, June, October, November and December (4mi).
