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
In Roslyn, the month of December is known for its lowest average temperatures, reaching a high of 29.7°F (-1.3°C) and a low of 18.3°F (-7.6°C).Humidity
In December, the average relative humidity is 91%.Rainfall
In Roslyn, Washington, 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
January through May, September through December are months with snowfall in Roslyn, Washington. In Roslyn, in December, during 15.1 snowfall days, 15.24" (387mm) of snow is typically accumulated. Throughout the year, there are 69.9 snowfall days, and 60.24" (1530mm) of snow is accumulated.Daylight
The month with the shortest days is December, 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
In December, the average sunshine is 3.7h.UV index
January, February, November and December, with an average maximum UV index of 1, are months with the lowest UV index. A UV Index value of 2, and less, symbolizes a minimal health hazard from exposure to the Sun's UV radiation for the average person.Note: A daily maximum UV index of 1 in December translates into the following instructions:
While many people can endure lengthy sun exposure, it remains imperative to safeguard babies, children, and fair-skinned individuals. When the Sun is at its strongest around midday, find shade and limit exposure. Experience reduced UV exposure by about half when donning a wide-brim hat. Be advised! The UV radiation from the Sun can be almost doubled due to the reflective properties of snow.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the coldest month?
How cold is it in Roslyn in December?
What is the average humidity in December?
How much does it rain in December?
How many days does it snow in December?
What is the month with the shortest days?
What is the average length of the day in December?
What time are sunrise and sunset in December?
How long on average sun shines in December?
What is the month with the lowest UV index in Roslyn?
What is the UV index reading 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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