December weather forecast
Sisters, OR

Weather in December

December, the first month of the winter in Sisters, is also a wintry month, with an average temperature ranging between min 24.8°F (-4°C) and max 36.5°F (2.5°C).

Temperature

With an average high-temperature of 36.5°F (2.5°C) and an average low-temperature of 24.8°F (-4°C), December is the coldest month.

Humidity

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

Rainfall

In Sisters, during December, the rain falls for 13 days and regularly aggregates up to 3.15" (80mm) of precipitation. In Sisters, during the entire year, the rain falls for 142.1 days and collects up to 22.87" (581mm) of precipitation.

Snowfall

Months with snowfall in Sisters are January through May, September through December. In Sisters, during December, snow falls for 14.7 days and regularly aggregates up to 10.75" (273mm) of snow. Throughout the year, in Sisters, there are 70.7 snowfall days, and 60.04" (1525mm) of snow is accumulated.

Daylight

With an average of 8h and 55min of daylight, December has the shortest days of the year.
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, in Sisters, sunrise is at 7:41 am and sunset at 4:36 pm PST.

Sunshine

December has the least sunshine of the year, with an average of 5.1h of sunshine.

UV index

The average daily maximum UV index in December in Sisters is 2. A UV Index of 2, and less, symbolizes a low health risk from exposure to the Sun's UV rays for the ordinary person.
Note: In December, the average maximum UV index of 2 translate into the following recommendations:
For the majority, extended sun exposure is not of great concern. Infants and people with sensitive skin must always be protected. The solar radiation is most powerful near the mid-day, so the exposure to the direct Sun should be reduced accordingly. Sun-protective clothing, a long-sleeved shirt and pants, a wide-brimmed hat, and UVA and UVB-blocking sunglasses are particularly helpful in blocking UV radiation's harmful effects. Caution! The reflection of snow can nearly double the intensity of the Sun's UV radiation.
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FAQ

What is the coldest month in Sisters?

December is the coldest month in Sisters, with an average high-temperature of 36.5°F (2.5°C) and an average low-temperature of 24.8°F (-4°C).

What is the most humid month in Sisters?

December is the most humid month in Sisters, Oregon, 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 much does it rain in Sisters in December?

In Sisters, in December, during 13 rainfall days, 3.15" (80mm) of precipitation is typically accumulated.

How many days does it snow in December in Sisters?

In December, in Sisters, Oregon, it is snowing for 14.7 days. Throughout December, 10.75" (273mm) of snow is accumulated.

What is the month with the shortest days in Sisters?

December has the shortest days of the year, with an average of 8h and 55min of daylight.

How many hours of daylight does Sisters have in December?

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

When are sunrise and sunset in December in Sisters?

On the first day of December in Sisters, sunrise is at 7:22 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.

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, Oregon.

How long on average sun shines in December in Sisters?

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

How high is the UV index in December in Sisters?

In December, the average daily maximum UV index in Sisters is 2. A UV Index reading of 2, and below, represents a minimal health vulnerability from unsafe exposure to Sun's UV rays.
Average humidity
Average rainfall days
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

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 55min

The month with the longest days is June (Average daylight: 15h and 28min).
The month with the shortest days is December (Average daylight: 8h and 55min).

  • 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).

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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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