December weather forecast
Sisters, OR

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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. 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

Sisters's coldest month, December, generally records average temperatures ranging from a high of 36.5°F to a low of 24.8°F.

Humidity

December is the most humid month in Sisters, with an average relative humidity of 84%.

Rainfall

In Sisters, in December, it is raining for 13 days, with typically 3.15" of accumulated precipitation. In Sisters, during the entire year, the rain falls for 142.1 days and collects up to 22.87" of precipitation.

Snowfall

January through May, September through December are months with snowfall. In Sisters, during December, snow falls for 14.7 days and regularly aggregates up to 10.75" of snow. Throughout the year, there are 70.7 snowfall days, and 60.04" 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 December, sunrise is at 7:21 am and sunset at 4:28 pm. On the last day of the month, sunrise is at 7:41 am and sunset at 4:36 pm PST.

Sunshine

The month with the least sunshine is December, 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 value of 2, and less, symbolizes a minimal health vulnerability from exposure to the Sun's UV radiation for average individuals.
Note: During December, 2 as the daily maximum UV index converts into the following advice:
Protection from prolonged sun exposure is necessary for babies, children, and individuals with sensitive skin. When the Sun is at its strongest around midday, find shade and limit exposure. Fend off the sun's harsh rays with appropriate clothing, a wide-brim hat, and UV-protective sunglasses. Beware! The strength of the UV rays is increased nearly double-fold by the reflection of the snow.
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FAQ

What is the coldest time of year in Sisters?

December is the coldest month in Sisters, with an average high-temperature of 36.5°F and an average low-temperature of 24.8°F.

How cold is it in Sisters in December?

In December, the average high-temperature and low-temperature are 36.5°F and 24.8°F respectively.

What is the most humid month in Sisters?

The most humid month in Sisters is December, with an average relative humidity of 84%.

What is the average humidity in December in Sisters?

In Sisters, the average relative humidity in December is 84%.

How many days does it rain in December in Sisters?

In Sisters, Oregon, in December, it is raining for 13 days, with typically 3.15" of accumulated precipitation.

How much does it snow in Sisters in December?

In Sisters, Oregon, in December, snow falls for 14.7 days, with typically accumulated 10.75" of snow.

What is the month with the shortest days in Sisters?

The month with the shortest days is December, with an average of 8h and 54min of daylight.

How many hours of daylight does Sisters have in December?

In December, the average day length in Sisters, Oregon, is 8h and 55min.

When are sunrise and sunset in December in Sisters?

In December, on the first day of the month, sunrise is at 7:21 am and sunset at 4:28 pm. On the last day of the month, in Sisters, Oregon, sunrise is at 7:41 am and sunset at 4:36 pm PST.

What is the month with the least sunshine in Sisters?

With an average of 5.1h of sunshine, December has the least sunshine of the year in Sisters.

How many hours of sunshine does Sisters have in December?

In Sisters, the average sunshine duration in December is 5.1h.

What is the UV index intensity in December in Sisters?

In Sisters, Oregon, the average daily maximum UV index in December is 2. A UV Index of 2, and less, symbolizes a low health risk from unsafe exposure to Sun's UV rays.
Today
Tomorrow
Long-term
YearJFMAMJJASONDecember
Nov
December
Jan
Average high temperature
44.2°F
36.5°F
39°F
Average low temperature
31.1°F
24.8°F
26.6°F
Average pressure
30.09"Hg
30.14"Hg
30.16"Hg
Average wind speed
5.9mph
5.8mph
5.8mph
Average max. wind speed
6.5mph
6.3mph
6.4mph
Average wind speed gusts
9.9mph
10.1mph
10.3mph
Average humidity
78%
84%
83%
Average rainfall
2.2"
3.15"
3.31"
Average rainfall days
13
13
12.8
Average snowfall
7.2"
10.75"
12.09"
Average snowfall days
7.8
14.7
11.2
Average daylight
9h 4min
8h 5min
9h 2min
Average sunshine
6h 1min
5h 1min
5h 1min
Average sunshine days
11.8
11.1
12.3
Average UV index
2
2
2
Average cloud cover
41%
49%
49%
Average visibility
6mi
5mi
5mi

Average temperature in December
Sisters, OR

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).

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Average pressure in December
Sisters, OR

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).

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Average wind speed in December
Sisters, OR

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).

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Average humidity in December
Sisters, OR

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%).

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Average rainfall in December
Sisters, OR

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").

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Average rainfall days in December
Sisters, OR

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).

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Average snowfall in December
Sisters, OR

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").

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Average snowfall days in December
Sisters, OR

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).

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Average daylight in December /
Average sunshine in December
Sisters, OR

Average daylight in December / Average sunshine in December - Sisters, OR
  • Average daylight in December: 8h and 5min

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 1min

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).

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Average sunshine days in December
Sisters, OR

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).

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Average UV index in December
Sisters, OR

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).

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Average cloud cover in December
Sisters, OR

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).

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Average visibility in December
Sisters, OR

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).

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Sisters, Oregon, USA

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