December weather forecastSammamish, WA
December
Weather in December
December marks the pinnacle of winter in Sammamish, characterised by the year’s lowest average temperature, falling to 33.6°F (0.9°C). The season brings forth a mild amount of snowfall, with the city receiving 0.35" (9mm) in December, creating a white winter spectacle. The increase in relative humidity to 85% indicates higher moisture content in the atmosphere, in line with the winter season. The daylight hours are at their shortest in December, while the pressure reaches its yearly peak of 30.09 in. Despite the cold, the festive spirit of the city sparkles through making it a prime attraction for holiday travelers.Temperature
The month of December sees the lowest average temperatures, reaching 42.3°F (5.7°C) at the peak and 33.6°F (0.9°C) at the low.Humidity
January, February and December, with an average relative humidity of 85%, are the most humid months.Rainfall
December is the month with the most rainfall. Rain falls for 14.1 days and accumulates 1.85" (47mm) of precipitation.Snowfall
Months with snowfall are January through April, November and December. In Sammamish, Washington, during December, snow falls for 1.3 days and regularly aggregates up to 0.35" (9mm) of snow. Throughout the year, there are 9.3 snowfall days, and 3.27" (83mm) of snow is accumulated.Daylight
With an average of 8h and 30min of daylight, December has the shortest days of the year.On the first day of the month, sunrise is at 7:36 am and sunset at 4:18 pm. On the last day of December, sunrise is at 7:56 am and sunset at 4:26 pm PST.
Sunshine
The months with the least sunshine are January and December, with an average of 4.2h of sunshine.UV index
January, February, November and December, with an average maximum UV index of 2, are months with the lowest UV index. A UV Index value of 2, and less, symbolizes a low health risk from unsafe exposure to UV radiation for ordinary individuals.Note: A maximum high UV index of 2 in December translates into the following recommendations:
Extended sun exposure is not an issue for the majority. Children, infants, and fair-skinned individuals always need to be protected. The Sun's most intense and consequently most harmful UV radiation during midday hours should be decreased by minimizing exposure and seeking shade. On sunny days, it's ideal to wear sunglasses that filter out UVA and UVB rays. Pay attention! The reflection of snow can enhance the Sun's UV radiation almost double.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in December
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
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
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
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
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
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
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
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
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
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
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
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
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).
