December weather forecastSumas, WA
December
Weather in December
The first month of the winter, December, is still a cold month in Sumas, Washington, with an average temperature ranging between min 31.6°F (-0.2°C) and max 39.6°F (4.2°C).Temperature
December, noted for its average high-temperature of 39.6°F (4.2°C) and an average low-temperature of 31.6°F (-0.2°C), is considered the coldest month.Humidity
In December, the average relative humidity in Sumas, Washington, is 86%.Rainfall
In Sumas, in December, it is raining for 19.2 days, with typically 6.85" (174mm) of accumulated precipitation. In Sumas, during the entire year, the rain falls for 188 days and collects up to 49.88" (1267mm) of precipitation.Snowfall
Months with snowfall are January through April, November and December. In Sumas, in December, during 3 snowfall days, 1.89" (48mm) of snow is typically accumulated. In Sumas, during the entire year, snow falls for 14.7 days and aggregates up to 10.2" (259mm) of snow.Daylight
The month with the shortest days in Sumas is December, with an average of 8h and 18min of daylight.On the first day of the month, sunrise is at 7:42 am and sunset at 4:14 pm. On the last day of December, in Sumas, sunrise is at 8:02 am and sunset at 4:21 pm PST.
Sunshine
The month with the least sunshine is December, with an average of 3.8h of sunshine.UV index
The months with the lowest UV index are January, February, October through December, with an average maximum UV index of 2. A UV Index estimate of 2, and below, represents a low threat to health from unprotected exposure to Sun's UV rays for average individuals.Note: A daily high UV index of 2 in December leads to these guidelines:
While most people can stay under the sun for an hour without burning, children must always be guarded against sun exposure. Limiting sun exposure during midday hours helps in reducing the harmful effects of UV radiation. For minimizing sun-related eye damage, always choose sunglasses with UVA and UVB coverage. Observe! Snow reflection can nearly intensify the Sun's UV radiation twofold.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in December
Sumas, WA
- Average high temperature in December: 39.6°F
The warmest month (with the highest average high temperature) is August (73.6°F).
The month with the lowest average high temperature is December (39.6°F).
- Average low temperature in December: 31.6°F
The month with the highest average low temperature is August (51.4°F).
The coldest months (with the lowest average low temperature) are February and December (31.6°F).
Average pressure in December
Sumas, 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 and August (30"Hg).
Average wind speed in December
Sumas, WA
- Average wind speed in December: 4.5mph
The windiest months (with the highest average wind speed) are January and February (4.7mph).
The calmest month (with the lowest average wind speed) is August (3.2mph).
Average humidity in December
Sumas, WA
- Average humidity in December: 86%
The month with the highest relative humidity is January (87%).
The month with the lowest relative humidity is July (73%).
Average rainfall in December
Sumas, WA
- Average rainfall in December: 6.85"
The wettest month (with the highest rainfall) is November (7.72").
The driest month (with the least rainfall) is July (0.91").
Average rainfall days in December
Sumas, WA
- Average rainfall days in December: 19.2 days
The month with the highest number of rainy days is March (20.5 days).
The month with the least rainy days is August (7.8 days).
Average snowfall in December
Sumas, WA
- Average snowfall in December: 1.89"
The month with the highest snowfall is February (3.11").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in December
Sumas, WA
- Average snowfall days in December: 3 days
The month with the highest number of snowfall days is February (4.7 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
Sumas, WA
- Average daylight in December: 8h and 18min
The month with the longest days is June (Average daylight: 16h and 6min).
The month with the shortest days is December (Average daylight: 8h and 18min).
- Average sunshine in December: 3h and 48min
The month with the most sunshine is August (Average sunshine: 10h and 18min).
The month with the least sunshine is December (Average sunshine: 3h and 48min).
Average sunshine days in December
Sumas, WA
- Average sunshine days in December: 10.3 days
The months with the most sunshine days are July and August (21 days).
The month with the least sunshine days is March (8.4 days).
Average UV index in December
Sumas, WA
- Average UV index in December: 2
The month with the highest UV index is July (UV index 5).
The months with the lowest UV index are January, February, October, November and December (UV index 2).
Average cloud cover in December
Sumas, WA
- Average cloud cover in December: 59
The month with the most cloud cover is March (Cloud cover 60).
The months with the least cloud cover are July and August (Cloud cover 30).
Average visibility in December
Sumas, WA
- Average visibility in December: 4mi
The months with the highest visibility are April, May, June, July, August, September and October (5mi).
The months with the lowest visibility are January, February, March, November and December (4mi).
