December weather forecastSisters, OR
December
Weather in December
As December rolls in, Sisters, Oregon finally gives in to winter’s clasp. The mercury dips further to an average low of 36.5°F (2.5°C). The snowfall comes to the party uninvited and often lays the first instances of a white blanket over the city. Concurrently, daylight diminishes, capping off the year with fewer sunlight hours. Though December carries a charm of its own, a festive spirit marred by chills, it's wise to layer-up and stay warm in the buzzing anticipation of the New Year approaching.Temperature
December is the month when Sisters sees the lowest average temperatures, with a high of 36.5°F (2.5°C) and a low of 24.8°F (-4°C).Humidity
With an average relative humidity of 84%, December is the most humid month.Rainfall
In Sisters, during December, the rain falls for 13 days and regularly aggregates up to 3.15" (80mm) of precipitation. Throughout the year, there are 142.1 rainfall days, and 22.87" (581mm) of precipitation is accumulated.Snowfall
January through May, September through December are months with snowfall. In December, it is snowing for 14.7 days. Throughout December, 10.75" (273mm) of snow is accumulated. Throughout the year, there are 70.7 snowfall days, and 60.04" (1525mm) of snow is accumulated.Daylight
The month with the shortest days is December, with an average of 8h and 54min of daylight.On the first day of the month, sunrise is at 7:22 am and sunset at 4:28 pm. On the last day of December, sunrise is at 7:41 am and sunset at 4:37 pm PST.
Sunshine
December has the least sunshine of the year, with an average of 5.1h of sunshine.UV index
In Sisters, the average daily maximum UV index in December is 2. A UV Index of 2, and less, symbolizes a low threat to health from exposure to the Sun's UV radiation for the average person.Note: The maximum daily UV index of 2 in December converts into the following recommendations:
While most people can stay under the sun for an hour without burning, children must always be guarded against sun exposure. For health reasons, it's advisable to reduce direct sun exposure during peak hours around midday. For effective sun eye protection, rely on sunglasses certified for UVA and UVB resistance. Note well! The intensity of the Sun's UV rays can be nearly doubled by snow reflection.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in December
Sisters, OR
- Average high temperature in December: 36.5°F
The warmest month (with the highest average high temperature) is July (78.8°F).
The month with the lowest average high temperature is December (36.5°F).
- Average low temperature in December: 24.8°F
The month with the highest average low temperature is August (50.7°F).
The coldest month (with the lowest average low temperature) is December (24.8°F).
Average pressure in December
Sisters, OR
- Average pressure in December: 30.14"Hg
The month with the highest atmospheric pressure is January (30.16"Hg).
The month with the lowest atmospheric pressure is August (29.98"Hg).
Average wind speed in December
Sisters, OR
- Average wind speed in December: 5.8mph
The windiest month (with the highest average wind speed) is February (6.1mph).
The calmest months (with the lowest average wind speed) are August and September (4.8mph).
Average humidity in December
Sisters, OR
- Average humidity in December: 84%
The month with the highest relative humidity is December (84%).
The months with the lowest relative humidity are July and August (53%).
Average rainfall in December
Sisters, OR
- Average rainfall in December: 3.15"
The wettest month (with the highest rainfall) is January (3.31").
The driest month (with the least rainfall) is July (0.35").
Average rainfall days in December
Sisters, OR
- Average rainfall days in December: 13 days
The month with the highest number of rainy days is March (16.9 days).
The month with the least rainy days is July (5 days).
Average snowfall in December
Sisters, OR
- Average snowfall in December: 10.75"
The month with the highest snowfall is February (13.74").
The months with the least snowfall are June, July and August (0").
Average snowfall days in December
Sisters, OR
- Average snowfall days in December: 14.7 days
The month with the highest number of snowfall days is December (14.7 days).
The months with the least snowfall days are June, July and August (0 days).
Average daylight in December /
Average sunshine in December
Sisters, OR
- Average daylight in December: 8h and 54min
The month with the longest days is June (Average daylight: 15h and 30min).
The month with the shortest days is December (Average daylight: 8h and 54min).
- Average sunshine in December: 5h and 6min
The month with the most sunshine is July (Average sunshine: 12h and 0min).
The month with the least sunshine is December (Average sunshine: 5h and 6min).
Average sunshine days in December
Sisters, OR
- Average sunshine days in December: 11.1 days
The month with the most sunshine days is July (23.3 days).
The month with the least sunshine days is March (8.1 days).
Average UV index in December
Sisters, OR
- Average UV index in December: 2
The month with the highest UV index is July (UV index 6).
The month with the lowest UV index is February (UV index 1).
Average cloud cover in December
Sisters, OR
- Average cloud cover in December: 49
The months with the most cloud cover are January, February, March and December (Cloud cover 49).
The month with the least cloud cover is July (Cloud cover 11).
Average visibility in December
Sisters, OR
- Average visibility in December: 5mi
The months with the highest visibility are April, May, June, July, August, September, October and November (6mi).
The months with the lowest visibility are January, February, March and December (5mi).
