December weather forecastWest Lake Sammamish, WA
December
Weather in December
The first month of the winter, December, is also an icy month in West Lake Sammamish, Washington, with an average temperature varying between 42.3°F (5.7°C) and 33.6°F (0.9°C).Temperature
Temperature records mark December as the coldest month, with highs averaging 42.3°F (5.7°C) and lows at 33.6°F (0.9°C).Humidity
January, February and December, with an average relative humidity of 85%, are the most humid months.Rainfall
The month with the most rainfall is December, when the rain falls for 14.1 days and typically aggregates up to 1.85" (47mm) of precipitation.Snowfall
Months with snowfall are January through April, November and December. In West Lake Sammamish, in December, during 1.3 snowfall days, 0.35" (9mm) of snow is typically accumulated. Throughout the year, there are 9.3 snowfall days, and 3.27" (83mm) of snow is accumulated.Daylight
December has the shortest days of the year, with an average of 8h and 30min of daylight.On the first day of the month, sunrise is at 7:36 am and sunset at 4:19 pm. On the last day of December, sunrise is at 7:56 am and sunset at 4:27 pm PST.
Sunshine
January and December, with an average of 4.2h of sunshine, are months with the least sunshine.UV index
The months with the lowest UV index are January, February, November and December, with an average maximum UV index of 2. A UV Index value of 2, and less, symbolizes a minimal health hazard from unprotected exposure to Sun's UV rays for the ordinary person.Note: A daily maximum UV index of 2 in December translates into the following instructions:
Extended time in the sun generally does not harm most, but those with sensitive skin, infants, and children should always be protected. The intensity of the Sun's UV radiation during midday suggests reducing time spent outdoors. Experience reduced UV exposure by about half when donning a wide-brim hat. Remember! The Sun's UV radiation can be magnified almost twofold by the reflection of snow.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in December
West Lake Sammamish, WA
- Average high temperature in December: 42.3°F
The warmest month (with the highest average high temperature) is August (76.5°F).
The month with the lowest average high temperature is December (42.3°F).
- Average low temperature in December: 33.6°F
The month with the highest average low temperature is August (52.2°F).
The coldest month (with the lowest average low temperature) is December (33.6°F).
Average pressure in December
West Lake Sammamish, WA
- Average pressure in December: 30.09"Hg
The month with the highest atmospheric pressure is January (30.1"Hg).
The month with the lowest atmospheric pressure is August (30"Hg).
Average wind speed in December
West Lake Sammamish, WA
- Average wind speed in December: 4.6mph
The windiest month (with the highest average wind speed) is January (5mph).
The calmest month (with the lowest average wind speed) is August (3.4mph).
Average humidity in December
West Lake Sammamish, WA
- Average humidity in December: 85%
The months with the highest relative humidity are January, February and December (85%).
The month with the lowest relative humidity is July (70%).
Average rainfall in December
West Lake Sammamish, WA
- Average rainfall in December: 1.85"
The wettest month (with the highest rainfall) is December (1.85").
The driest months (with the least rainfall) are July and August (0.35").
Average rainfall days in December
West Lake Sammamish, WA
- Average rainfall days in December: 14.1 days
The month with the highest number of rainy days is March (14.8 days).
The month with the least rainy days is August (5.2 days).
Average snowfall in December
West Lake Sammamish, WA
- Average snowfall in December: 0.35"
The month with the highest snowfall is February (1.38").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in December
West Lake Sammamish, WA
- Average snowfall days in December: 1.3 days
The month with the highest number of snowfall days is February (3.2 days).
The months with the least snowfall days are May, June, July, August and October (0 days).
Average daylight in December /
Average sunshine in December
West Lake Sammamish, WA
- Average daylight in December: 8h and 30min
The month with the longest days is June (Average daylight: 15h and 54min).
The month with the shortest days is December (Average daylight: 8h and 30min).
- Average sunshine in December: 4h and 12min
The month with the most sunshine is August (Average sunshine: 10h and 42min).
The months with the least sunshine are January and December (Average sunshine: 4h and 12min).
Average sunshine days in December
West Lake Sammamish, WA
- Average sunshine days in December: 15.2 days
The month with the most sunshine days is August (24 days).
The month with the least sunshine days is November (13.5 days).
Average UV index in December
West Lake Sammamish, WA
- Average UV index in December: 2
The months with the highest UV index are June and July (UV index 5).
The months with the lowest UV index are January, February, November and December (UV index 2).
Average cloud cover in December
West Lake Sammamish, WA
- Average cloud cover in December: 57
The month with the most cloud cover is December (Cloud cover 57).
The month with the least cloud cover is August (Cloud cover 26).
Average visibility in December
West Lake Sammamish, WA
- Average visibility in December: 5mi
The months with the highest visibility are June, July, August and September (6mi).
The months with the lowest visibility are January, February, March, April, May, October, November and December (5mi).
