December weather forecastRoy, WA
December
Weather in December
The first month of the winter, December, is still a chilly month in Roy, Washington, with an average temperature fluctuating between 43.5°F (6.4°C) and 34.2°F (1.2°C).Temperature
December stands out as Roy's coldest month, with temperatures ranging between an average high of 43.5°F (6.4°C) and a low of 34.2°F (1.2°C).Humidity
In Roy, the average relative humidity in December is 87%.Rainfall
The month with the most rainfall in Roy is December, when the rain falls for 18.6 days and typically aggregates up to 4.96" (126mm) of precipitation.Snowfall
January through April, November and December are months with snowfall. In Roy, during December, snow falls for 1.4 days and regularly aggregates up to 0.24" (6mm) of snow. In Roy, during the entire year, snow falls for 7.9 days and aggregates up to 4.45" (113mm) of snow.Daylight
With an average of 8h and 36min of daylight, December has the shortest days of the year in Roy.On the first day of the month, sunrise is at 7:36 am and sunset at 4:22 pm. On the last day of December, in Roy, Washington, sunrise is at 7:55 am and sunset at 4:31 pm PST.
Sunshine
With an average of 3.9h of sunshine, December has the least sunshine of the year in Roy.UV index
January, February, November and December, with an average maximum UV index of 2, are months with the lowest UV index in Roy, Washington. A UV Index estimate of 2, and below, represents a minimal health hazard from unsafe exposure to UV radiation for the average person.Note: In December, a daily maximum UV index of 2 leads to the following instructions:
Most individuals face no major issues with lengthy exposure to the sun, but children, infants, and individuals with fair skin always require protection. Direct Sun exposure should be minimized especially during midday when radiation is most intense. Shield yourself from the harmful effects of UV radiation with sun-protective attire, a hat, and quality sunglasses. Forewarned is forearmed! The Sun's UV radiation can be almost doubled in intensity by snow reflection.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in December
Roy, WA
- Average high temperature in December: 43.5°F
The warmest month (with the highest average high temperature) is August (78.4°F).
The month with the lowest average high temperature is December (43.5°F).
- Average low temperature in December: 34.2°F
The month with the highest average low temperature is August (52.2°F).
The coldest month (with the lowest average low temperature) is February (34°F).
Average pressure in December
Roy, WA
- Average pressure in December: 30.08"Hg
The month with the highest atmospheric pressure is January (30.09"Hg).
The months with the lowest atmospheric pressure are March, August and September (30.01"Hg).
Average wind speed in December
Roy, WA
- Average wind speed in December: 4.5mph
The windiest month (with the highest average wind speed) is March (5mph).
The calmest month (with the lowest average wind speed) is August (3.7mph).
Average humidity in December
Roy, WA
- Average humidity in December: 87%
The month with the highest relative humidity is January (88%).
The month with the lowest relative humidity is July (69%).
Average rainfall in December
Roy, WA
- Average rainfall in December: 4.96"
The wettest month (with the highest rainfall) is December (4.96").
The driest month (with the least rainfall) is July (0.35").
Average rainfall days in December
Roy, WA
- Average rainfall days in December: 18.6 days
The month with the highest number of rainy days is March (19.7 days).
The month with the least rainy days is August (5.2 days).
Average snowfall in December
Roy, WA
- Average snowfall in December: 0.24"
The month with the highest snowfall is February (1.73").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in December
Roy, WA
- Average snowfall days in December: 1.4 days
The month with the highest number of snowfall days is February (2.8 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
Roy, WA
- Average daylight in December: 8h and 36min
The month with the longest days is June (Average daylight: 15h and 48min).
The month with the shortest days is December (Average daylight: 8h and 36min).
- Average sunshine in December: 3h and 54min
The month with the most sunshine is August (Average sunshine: 10h and 36min).
The month with the least sunshine is December (Average sunshine: 3h and 54min).
Average sunshine days in December
Roy, WA
- Average sunshine days in December: 10.1 days
The month with the most sunshine days is August (22.9 days).
The month with the least sunshine days is November (9.1 days).
Average UV index in December
Roy, WA
- 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
Roy, WA
- Average cloud cover in December: 59
The months with the most cloud cover are January and December (Cloud cover 59).
The months with the least cloud cover are July and August (Cloud cover 28).
Average visibility in December
Roy, WA
- Average visibility in December: 4mi
The months with the highest visibility are July and August (6mi).
The months with the lowest visibility are January, February and December (4mi).
