December weather forecastGrand Coulee, WA
December
Weather in December
The first month of the winter, December, is also a subzero cold month in Grand Coulee, Washington, with an average temperature fluctuating between 31.6°F (-0.2°C) and 21.4°F (-5.9°C).Temperature
Grand Coulee experiences its lowest average temperatures in December, reaching a peak of 31.6°F (-0.2°C) and a minimum of 21.4°F (-5.9°C).Humidity
In December, the average relative humidity is 86%.Rainfall
The months with the most rainfall are May and December, with an average 1.18" (30mm) of precipitation.Snowfall
January through April, September through December are months with snowfall. In Grand Coulee, in December, during 10.5 snowfall days, 3.78" (96mm) of snow is typically accumulated. In Grand Coulee, during the entire year, snow falls for 33.4 days and aggregates up to 14.65" (372mm) of snow.Daylight
December has the shortest days of the year in Grand Coulee, with an average of 8h and 30min of daylight.On the first day of December, sunrise is at 7:25 am and sunset at 4:05 pm. On the last day of the month, sunrise is at 7:45 am and sunset at 4:13 pm PST.
Sunshine
The average sunshine in December is 4.4h.UV index
In Grand Coulee, the average daily maximum UV index in December is 2. A UV Index value of 2, and less, symbolizes a low health risk from exposure to the Sun's UV radiation for average individuals.Note: In December, a regular UV index of 2 translates into these guidelines:
Extended sun exposure is not an issue for the majority. Children, infants, and fair-skinned individuals always need to be protected. UV radiation is strongest from the Sun during midday; protect yourself by staying in shaded areas. Consider a wide-brim hat essential for effective sun defense covering your face, neck, and eyes. Take precaution! The reflection from snow can almost double the UV radiation of the Sun.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in December
Grand Coulee, WA
- Average high temperature in December: 31.6°F
The warmest month (with the highest average high temperature) is July (84.9°F).
The month with the lowest average high temperature is December (31.6°F).
- Average low temperature in December: 21.4°F
The month with the highest average low temperature is August (61.3°F).
The coldest month (with the lowest average low temperature) is December (21.4°F).
Average pressure in December
Grand Coulee, WA
- Average pressure in December: 30.15"Hg
The month with the highest atmospheric pressure is January (30.18"Hg).
The month with the lowest atmospheric pressure is August (29.91"Hg).
Average wind speed in December
Grand Coulee, WA
- Average wind speed in December: 5mph
The windiest month (with the highest average wind speed) is April (7mph).
The calmest month (with the lowest average wind speed) is January (4.9mph).
Average humidity in December
Grand Coulee, WA
- Average humidity in December: 86%
The month with the highest relative humidity is January (89%).
The month with the lowest relative humidity is August (36%).
Average rainfall in December
Grand Coulee, WA
- Average rainfall in December: 1.18"
The wettest months (with the highest rainfall) are May and December (1.18").
The driest months (with the least rainfall) are July and August (0.2").
Average rainfall days in December
Grand Coulee, WA
- Average rainfall days in December: 8.5 days
The month with the highest number of rainy days is March (12.1 days).
The month with the least rainy days is August (3.2 days).
Average snowfall in December
Grand Coulee, WA
- Average snowfall in December: 3.78"
The month with the highest snowfall is January (4.41").
The months with the least snowfall are May, June, July and August (0").
Average snowfall days in December
Grand Coulee, WA
- Average snowfall days in December: 10.5 days
The month with the highest number of snowfall days is December (10.5 days).
The months with the least snowfall days are May, June, July and August (0 days).
Average daylight in December /
Average sunshine in December
Grand Coulee, WA
- Average daylight in December: 8h and 30min
The month with the longest days is June (Average daylight: 16h and 0min).
The month with the shortest days is December (Average daylight: 8h and 30min).
- Average sunshine in December: 4h and 24min
The month with the most sunshine is August (Average sunshine: 12h and 6min).
The month with the least sunshine is January (Average sunshine: 4h and 6min).
Average sunshine days in December
Grand Coulee, WA
- Average sunshine days in December: 16 days
The month with the most sunshine days is August (25.8 days).
The month with the least sunshine days is March (14.7 days).
Average UV index in December
Grand Coulee, WA
- Average UV index in December: 2
The month with the highest UV index is July (UV index 7).
The month with the lowest UV index is November (UV index 1).
Average cloud cover in December
Grand Coulee, WA
- Average cloud cover in December: 52
The month with the most cloud cover is January (Cloud cover 55).
The months with the least cloud cover are July and August (Cloud cover 12).
Average visibility in December
Grand Coulee, WA
- Average visibility in December: 4mi
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 and December (4mi).
