December weather forecast
Sonoma, CA

Neat rows of vines in a vineyard farm in Sonoma, California
Neat rows of vines in a vineyard farm in Sonoma, California

Weather in December

The first month of the winter, December, is still a cool month in Sonoma, California, with average temperature varying between 41.4°F (5.2°C) and 55°F (12.8°C).

Temperature

December is the coldest month, with an average high-temperature of 55°F (12.8°C) and an average low-temperature of 41.4°F (5.2°C).

Humidity

The average relative humidity in Sonoma, California, is 73%.

Rainfall

In Sonoma, California, in December, during 10.6 rainfall days, 2.72" (69mm) of precipitation is typically accumulated. In Sonoma, during the entire year, the rain falls for 73.3 days and collects up to 15.47" (393mm) of precipitation.

Daylight

December has the shortest days of the year in Sonoma, with an average of 9.5h of daylight.

Sunshine

The month with the least sunshine is December, with an average of 5.6h of sunshine.

UV index

January, February, November and December, with an average maximum UV index of 3, are months with the lowest UV index in Sonoma. A UV Index reading of 3 to 5 represents a moderate threat to health from unprotected exposure to the Sun's UV rays for the average person.
Note: In December, the average maximum UV index of 3 translate into the following recommendations:
Take precautions - Protection against the skin and eye damage is obliged. 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.
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FAQ

What is the coldest month in Sonoma?

December is the coldest month, with an average high-temperature of 55°F (12.8°C) and an average low-temperature of 41.4°F (5.2°C).

What is the average humidity in December in Sonoma?

In December, the average relative humidity is 73%.

How many days does it rain in December in Sonoma?

In Sonoma, California, in December, during 10.6 rainfall days, 2.72" (69mm) of precipitation is typically accumulated.

What is the month with the shortest days in Sonoma?

December has the shortest days of the year in Sonoma, California, with an average of 9.5h of daylight.

How many hours of daylight does Sonoma have in December?

The average length of the day in December is 9.5h.

What is the month with the least sunshine in Sonoma?

With an average of 5.6h of sunshine, December has the least sunshine of the year in Sonoma, California.

How long on average sun shines in December in Sonoma?

The average sunshine in December in Sonoma is 5.6h.

What are the months with the lowest UV index in Sonoma?

Months with the lowest UV index are January, February, November and December, with an average maximum UV index of 3.

What is the UV index intensity in December in Sonoma?

In December, the average daily maximum UV index in Sonoma is 3. A UV Index reading of 3 to 5 represents a medium health risk from unprotected exposure to the UV radiation.

Average temperature in December
Sonoma, CA

Average temperature in December - Sonoma, CA
  • Average high temperature in December: 12.8°C

The warmest month (with the highest average high temperature) is August (28.3°C).
The month with the lowest average high temperature is December (12.8°C).

  • Average low temperature in December: 5.2°C

The month with the highest average low temperature is August (12.7°C).
The coldest month (with the lowest average low temperature) is December (5.2°C).

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Average pressure in December
Sonoma, CA

Average pressure in December - Sonoma, CA
  • Average pressure in December: 1019.5mbar

The month with the highest atmospheric pressure is January (1020.4mbar).
The month with the lowest atmospheric pressure is June (1013mbar).

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Average wind speed in December
Sonoma, CA

Average wind speed in December - Sonoma, CA
  • Average wind speed in December: 7.8km/h

The windiest month (with the highest average wind speed) is May (10km/h).
The calmest month (with the lowest average wind speed) is November (7.1km/h).

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Average humidity in December
Sonoma, CA

Average humidity in December - Sonoma, CA
  • Average humidity in December: 73%

The month with the highest relative humidity is March (76%).
The month with the lowest relative humidity is September (59%).

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Average rainfall in December
Sonoma, CA

Average rainfall in December - Sonoma, CA
  • Average rainfall in December: 69mm

The wettest month (with the highest rainfall) is February (87mm).
The driest months (with the least rainfall) are July and August (1mm).

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Average rainfall days in December
Sonoma, CA

Average rainfall days in December - Sonoma, CA
  • Average rainfall days in December: 10.6 days

The month with the highest number of rainy days is March (13.4 days).
The month with the least rainy days is August (0.8 days).

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Average daylight in December /
Average sunshine in December
Sonoma, CA

Average daylight in December / Average sunshine in December - Sonoma, CA
  • Average daylight in December: 9.5h

The month with the longest days is June (Average daylight: 14.8h).
The month with the shortest days is December (Average daylight: 9.5h).

  • Average sunshine in December: 5.6h

The month with the most sunshine is July (Average sunshine: 12h).
The month with the least sunshine is December (Average sunshine: 5.6h).

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Average sunshine days in December
Sonoma, CA

Average sunshine days in December - Sonoma, CA
  • Average sunshine days in December: 19.4 days

The month with the most sunshine days is July (28.7 days).
The month with the least sunshine days is March (16.1 days).

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Average UV index in December
Sonoma, CA

Average UV index in December - Sonoma, CA
  • Average UV index in December: 3

Months with the highest UV index are June and July (UV index 6).
Months with the lowest UV index are January, February, November and December (UV index 3).

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Average cloud cover in December
Sonoma, CA

Average cloud cover in December - Sonoma, CA
  • Average cloud cover in December: 38

The month with the most cloud cover is March (Cloud cover 40).
The month with the least cloud cover is July (Cloud cover 8).

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Average visibility in December
Sonoma, CA

Average visibility in December - Sonoma, CA
  • Average visibility in December: 9km

Months with the highest visibility are June, July and September (10km).
Months with the lowest visibility are January, February, March, April, May, August, October, November and December (9km).

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