December weather forecastGrass Valley, OR
December
Weather in December
December, the first month of the winter in Grass Valley, is also an icy month, with an average temperature fluctuating between 27°F (-2.8°C) and 37.4°F (3°C).Temperature
December is the coldest month, with the temperature often reaching an average high of 37.4°F (3°C) and an average low of 27°F (-2.8°C).Humidity
In Grass Valley, the average relative humidity in December is 83%.Rainfall
In Grass Valley, in December, during 12.6 rainfall days, 1.73" (44mm) of precipitation is typically accumulated. In Grass Valley, during the entire year, the rain falls for 112.2 days and collects up to 10.91" (277mm) of precipitation.Snowfall
January through March, November and December are months with snowfall. In Grass Valley, during December, snow falls for 3.9 days and regularly aggregates up to 2.09" (53mm) of snow. Throughout the year, in Grass Valley, there are 12.6 snowfall days, and 7.6" (193mm) of snow is accumulated.Daylight
With an average of 8h and 48min of daylight, December has the shortest days of the year.On the first day of December, sunrise is at 7:23 am and sunset at 4:21 pm. On the last day of the month, sunrise is at 7:42 am and sunset at 4:30 pm PST.
Sunshine
In December, the average sunshine is 5.1h.UV index
January, February, November and December, with an average maximum UV index of 2, are months with the lowest UV index in Grass Valley. A UV Index estimate of 2, and below, represents a minimal health vulnerability from exposure to the Sun's UV radiation for average individuals.Note: The daily high UV index of 2 in December translates into this advice:
Those with sensitive skin, infants, and children require constant safeguarding from prolonged sun exposure. Minimize direct exposure to the Sun during midday when its radiation is at its peak. Employ a wide-brim hat for potent defense against up to 50% of UV rays. Take note! UV radiation from the Sun can double in intensity due to snow reflection.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in December
Grass Valley, OR
- Average high temperature in December: 37.4°F
The warmest month (with the highest average high temperature) is July (83.5°F).
The month with the lowest average high temperature is December (37.4°F).
- Average low temperature in December: 27°F
The month with the highest average low temperature is August (57.9°F).
The coldest month (with the lowest average low temperature) is December (27°F).
Average pressure in December
Grass Valley, OR
- Average pressure in December: 30.14"Hg
The month with the highest atmospheric pressure is January (30.16"Hg).
The month with the lowest atmospheric pressure is August (29.95"Hg).
Average wind speed in December
Grass Valley, OR
- Average wind speed in December: 5mph
The windiest month (with the highest average wind speed) is June (7.9mph).
The calmest months (with the lowest average wind speed) are January and December (5mph).
Average humidity in December
Grass Valley, OR
- Average humidity in December: 83%
The month with the highest relative humidity is January (84%).
The month with the lowest relative humidity is August (46%).
Average rainfall in December
Grass Valley, OR
- Average rainfall in December: 1.73"
The wettest month (with the highest rainfall) is January (1.93").
The driest month (with the least rainfall) is July (0.12").
Average rainfall days in December
Grass Valley, OR
- Average rainfall days in December: 12.6 days
The month with the highest number of rainy days is March (14.3 days).
The month with the least rainy days is July (2.9 days).
Average snowfall in December
Grass Valley, OR
- Average snowfall in December: 2.09"
The month with the highest snowfall is February (2.87").
The months with the least snowfall are April, May, June, July, August, September and October (0").
Average snowfall days in December
Grass Valley, OR
- Average snowfall days in December: 3.9 days
The months with the highest number of snowfall days are February and December (3.9 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
Grass Valley, OR
- Average daylight in December: 8h and 48min
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: 5h and 6min
The months with the most sunshine are July and August (Average sunshine: 12h and 0min).
The month with the least sunshine is January (Average sunshine: 5h and 0min).
Average sunshine days in December
Grass Valley, OR
- Average sunshine days in December: 13.8 days
The month with the most sunshine days is July (27 days).
The month with the least sunshine days is February (12.3 days).
Average UV index in December
Grass 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
Grass Valley, OR
- Average cloud cover in December: 46
The month with the most cloud cover is January (Cloud cover 49).
The months with the least cloud cover are July and August (Cloud cover 9).
Average visibility in December
Grass Valley, OR
- Average visibility in December: 5mi
The months with the highest visibility are March, April, May, June, July, August, September, October and November (6mi).
The months with the lowest visibility are January, February and December (5mi).
