Contents
- Weather in December
- Frequently asked questions
- Average temperature in December
- Average pressure in December
- Average wind speed in December
- Average humidity in December
- Average rainfall in December
- Average rainfall days in December
- Average snowfall in December
- Average snowfall days in December
- Average daylight in December
- Average sunshine in December
- Average sunshine days in December
- Average UV index in December
- Average cloud cover in December
- Average visibility in December
Weather in December
Temperature
December brings the lowest temperatures, with an average high of 29.7°F (-1.3°C) and an average low of 18.3°F (-7.6°C).Humidity
In December, the average relative humidity in Roslyn is 91%.Rainfall
In Roslyn, during December, the rain falls for 12.1 days and regularly aggregates up to 4.17" (106mm) of precipitation. Throughout the year, there are 161.2 rainfall days, and 28.46" (723mm) of precipitation is accumulated.Snowfall
Months with snowfall are January through May, September through December. In Roslyn, during December, snow falls for 15.1 days and regularly aggregates up to 15.24" (387mm) of snow. Throughout the year, in Roslyn, there are 69.9 snowfall days, and 60.24" (1530mm) of snow is accumulated.Daylight
December has the shortest days of the year, with an average of 8h and 36min of daylight.On the first day of the month, sunrise is at 7:30 am and sunset at 4:15 pm. On the last day of December, sunrise is at 7:50 am and sunset at 4:24 pm PST.
Sunshine
The average sunshine in December is 3.7h.UV index
The months with the lowest UV index in Roslyn are January, February, November and December, with an average maximum UV index of 1. A UV Index estimate of 2, and below, represents a low threat to health from exposure to the Sun's UV radiation for the average person.Note: A typical high UV index of 1 in December suggests the following recommendations:
Extended sun exposure is not an issue for the majority. Children, infants, and fair-skinned individuals always need to be protected. Solar radiation is at its peak intensity during midday, so it's advisable to stay indoors or in the shade. Tightly woven clothing, when worn loosely, shields effectively against the Sun. On your guard! Snow's reflection can almost double the intensity of the Sun's UV radiation.
Frequently asked questions
What is the coldest time of year in Roslyn?
How cold is December in Roslyn?
What is the average humidity in December in Roslyn?
How many days does it rain in December in Roslyn?
How many days does it snow in December in Roslyn?
What is the month with the shortest days in Roslyn?
What is the average length of the day in December in Roslyn?
What time are sunrise and sunset in December in Roslyn?
How many hours of sunshine does Roslyn have in December?
What are the months with the lowest UV index in Roslyn?
What is the UV index intensity in December in Roslyn?
Average temperature in December
Roslyn, WA
- Average high temperature in December: 29.7°F
The warmest month (with the highest average high temperature) is August (75.4°F).
The month with the lowest average high temperature is December (29.7°F).
- Average low temperature in December: 18.3°F
The month with the highest average low temperature is August (47.8°F).
The coldest month (with the lowest average low temperature) is December (18.3°F).
Average pressure in December
Roslyn, WA
- Average pressure in December: 30.12"Hg
The month with the highest atmospheric pressure is January (30.14"Hg).
The month with the lowest atmospheric pressure is August (29.96"Hg).
Average wind speed in December
Roslyn, WA
- Average wind speed in December: 4.2mph
The windiest month (with the highest average wind speed) is June (6.7mph).
The calmest month (with the lowest average wind speed) is December (4.2mph).
Average humidity in December
Roslyn, WA
- Average humidity in December: 91%
The months with the highest relative humidity are January and February (92%).
The months with the lowest relative humidity are July and August (60%).
Average rainfall in December
Roslyn, WA
- Average rainfall in December: 4.17"
The wettest month (with the highest rainfall) is January (4.41").
The driest month (with the least rainfall) is July (0.39").
Average rainfall days in December
Roslyn, WA
- Average rainfall days in December: 12.1 days
The months with the highest number of rainy days are March and April (18.3 days).
The month with the least rainy days is August (5.5 days).
Average snowfall in December
Roslyn, WA
- Average snowfall in December: 15.24"
The month with the highest snowfall is January (16.3").
The months with the least snowfall are June, July and August (0").
Average snowfall days in December
Roslyn, WA
- Average snowfall days in December: 15.1 days
The month with the highest number of snowfall days is December (15.1 days).
The months with the least snowfall days are June, July and August (0 days).
Average daylight in December /
Average sunshine in December
Roslyn, WA
- Average daylight in December: 8h and 4min
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 36min).
- Average sunshine in December: 3h and 4min
The month with the most sunshine is August (Average sunshine: 11h and 54min).
The month with the least sunshine is January (Average sunshine: 3h and 24min).
Average sunshine days in December
Roslyn, WA
- Average sunshine days in December: 10.2 days
The month with the most sunshine days is August (22.8 days).
The month with the least sunshine days is February (6.8 days).
Average UV index in December
Roslyn, WA
- Average UV index in December: 1
The month with the highest UV index is July (UV index 5).
The months with the lowest UV index are January, February, November and December (UV index 1).
Average cloud cover in December
Roslyn, WA
- Average cloud cover in December: 62
The month with the most cloud cover is January (Cloud cover 63).
The months with the least cloud cover are July and August (Cloud cover 18).
Average visibility in December
Roslyn, WA
- Average visibility in December: 4mi
The months with the highest visibility are May, June, July, August and September (6mi).
The month with the lowest visibility is January (3mi).
Roslyn, Washington, USA
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