December weather forecast
Mount Shasta, CA

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The Lake Siskiyou on the base of Mount Shasta in California, and a view of the planted forest, the far suspension bridge, and snowy mountain peak
The Lake Siskiyou on the base of Mount Shasta in California, and a view of the planted forest, the far suspension bridge, and snowy mountain peak

Weather in December

December, the first month of the winter in Mount Shasta, is still a cold month, with an average temperature varying between 27.1°F (-2.7°C) and 40.8°F (4.9°C).

Temperature

Mount Shasta's coldest month, December, registers temperatures that range from a high of 40.8°F (4.9°C) to a low of 27.1°F (-2.7°C).

Humidity

The average relative humidity in December is 79%.

Rainfall

In Mount Shasta, in December, during 9.5 rainfall days, 4.02" (102mm) of precipitation is typically accumulated. In Mount Shasta, California, during the entire year, the rain falls for 90.7 days and collects up to 26.38" (670mm) of precipitation.

Snowfall

Months with snowfall in Mount Shasta, California, are January through May, September through December. In December, it is snowing for 10.9 days. Throughout December, 12.68" (322mm) of snow is accumulated. Throughout the year, there are 50.2 snowfall days, and 81.42" (2068mm) of snow is accumulated.

Daylight

The month with the shortest days is December, with an average of 9h and 18min of daylight.
On the first day of December, sunrise is at 7:16 am and sunset at 4:40 pm. On the last day of the month, sunrise is at 7:34 am and sunset at 4:50 pm PST.

Sunshine

December has the least sunshine of the year, with an average of 5.4h of sunshine.

UV index

January through March, November and December, with an average maximum UV index of 2, are months with the lowest UV index. A UV Index of 2, and less, symbolizes a minimal health hazard from exposure to the Sun's UV radiation for the average person.
Note: In December, the maximum UV index of 2 translates into these guidelines:
Long-term sun exposure is typically not a concern for most. However, those with sensitive skin, infants, and children must always have protection. Avoiding the Sun's peak radiation during midday hours is essential for health and safety. A wide-brim hat offers excellent sun protection for the eyes, ears, face, and neck. Sunglasses with UVA and UVB protection significantly reduce eye damage from sun exposure. Watch out! The Sun's UV radiation can be nearly magnified twofold due to snow reflection.
Updated: Jul 30, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What is the coldest month in Mount Shasta?

In Mount Shasta, December is the month with the lowest recorded average temperatures, measuring a high of 40.8°F (4.9°C) and a low of 27.1°F (-2.7°C).

Is December cold?

The high-temperature, in December, in Mount Shasta, is 40.8°F (4.9°C), while the low-temperature averages to 27.1°F (-2.7°C). The average heat index (a.k.a. 'feels like', 'real feel'), which takes the relative humidity and factors it into the air temperature reading, in August is calculated to be 84.2°F (29°C).

What is the average humidity in December?

The average relative humidity in December is 79%.

How much does it rain in December?

In December, the rain falls for 9.5 days. Throughout December, 4.02" (102mm) of precipitation is accumulated.

How many days does it snow in December?

In Mount Shasta, during December, snow falls for 10.9 days and regularly aggregates up to 12.68" (322mm) of snow.

What is the month with the shortest days?

December has the shortest days of the year in Mount Shasta, with an average of 9h and 18min of daylight.

What is the average length of the day in December?

In December, the average day length is 9h and 15min.

When is the sunrise / sunset in December in Mount Shasta?

On the first day of December in Mount Shasta, sunrise is at 7:16 am and sunset at 4:40 pm. On the last day of the month, sunrise is at 7:34 am and sunset at 4:50 pm PST.

What is the month with the least sunshine?

December has the least sunshine of the year, with an average of 5.4h of sunshine.

How long on average sun shines in December?

In December, the average sunshine duration is 5.4h.

When is the lowest UV index?

January through March, November and December, with an average maximum UV index of 2, are months with the lowest UV index.

How high is the UV index in December?

The average daily maximum UV index in December is 2. A UV Index value of 2, and less, symbolizes a minimal hazard to health from unprotected exposure to UV radiation.
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
Mount Shasta, CA

Average temperature in December - Mount Shasta, CA
  • Average high temperature in December: 40.8°F

The warmest month (with the highest average high temperature) is July (83.8°F).
The month with the lowest average high temperature is December (40.8°F).

  • Average low temperature in December: 27.1°F

The month with the highest average low temperature is July (52.2°F).
The coldest month (with the lowest average low temperature) is December (27.1°F).

Average pressure in December
Mount Shasta, CA

Average pressure in December - Mount Shasta, CA
  • Average pressure in December: 30.14"Hg

The month with the highest atmospheric pressure is January (30.17"Hg).
The months with the lowest atmospheric pressure are June and August (29.94"Hg).

Average wind speed in December
Mount Shasta, CA

Average wind speed in December - Mount Shasta, CA
  • Average wind speed in December: 5mph

The windiest month (with the highest average wind speed) is March (5.8mph).
The calmest month (with the lowest average wind speed) is August (3.9mph).

Average humidity in December
Mount Shasta, CA

Average humidity in December - Mount Shasta, CA
  • Average humidity in December: 79%

The month with the highest relative humidity is March (81%).
The month with the lowest relative humidity is August (45%).

Average rainfall in December
Mount Shasta, CA

Average rainfall in December - Mount Shasta, CA
  • Average rainfall in December: 4.02"

The wettest month (with the highest rainfall) is March (4.69").
The driest month (with the least rainfall) is July (0.16").

Average rainfall days in December
Mount Shasta, CA

Average rainfall days in December - Mount Shasta, CA
  • Average rainfall days in December: 9.5 days

The month with the highest number of rainy days is March (12.3 days).
The month with the least rainy days is August (2.3 days).

Average snowfall in December
Mount Shasta, CA

Average snowfall in December - Mount Shasta, CA
  • Average snowfall in December: 12.68"

The month with the highest snowfall is January (19.21").
The months with the least snowfall are June, July and August (0").

Average snowfall days in December
Mount Shasta, CA

Average snowfall days in December - Mount Shasta, CA
  • Average snowfall days in December: 10.9 days

The month with the highest number of snowfall days is December (10.9 days).
The months with the least snowfall days are July and August (0 days).

Average daylight in December /
Average sunshine in December
Mount Shasta, CA

Average daylight in December / Average sunshine in December - Mount Shasta, CA
  • Average daylight in December: 9h and 2min

The month with the longest days is June (Average daylight: 15h and 6min).
The month with the shortest days is December (Average daylight: 9h and 18min).

  • Average sunshine in December: 5h and 2min

The month with the most sunshine is July (Average sunshine: 12h and 6min).
The month with the least sunshine is December (Average sunshine: 5h and 24min).

Average sunshine days in December
Mount Shasta, CA

Average sunshine days in December - Mount Shasta, CA
  • Average sunshine days in December: 14.9 days

The months with the most sunshine days are July and August (25.7 days).
The month with the least sunshine days is March (12.3 days).

Average UV index in December
Mount Shasta, CA

Average UV index in December - Mount Shasta, CA
  • Average UV index in December: 2

The months with the highest UV index are June and July (UV index 6).
The months with the lowest UV index are January, February, March, November and December (UV index 2).

Average cloud cover in December
Mount Shasta, CA

Average cloud cover in December - Mount Shasta, CA
  • Average cloud cover in December: 43

The month with the most cloud cover is March (Cloud cover 45).
The month with the least cloud cover is August (Cloud cover 6).

Average visibility in December
Mount Shasta, CA

Average visibility in December - Mount Shasta, CA
  • 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).

Mount Shasta, California, USA

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