December weather forecast
Santa Rosa, CA

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Set in a scenic valley, the Camarillo region of Santa Rosa, California, has great modern homes and is neared by scenic rugged mountain layouts
Set in a scenic valley, the Camarillo region of Santa Rosa, California, has great modern homes and is neared by scenic rugged mountain layouts

Weather in December

Closing out the year, December in Santa Rosa epitomizes the winter season in the city. Though temperatures and daylight hours fall noticeably from November levels, the winter here is relatively mild and temperate. Correspondingly, the increase in rainfall from 1.02" to 2.24" in December highlights the winter imprint. Moreover, the increase in relative humidity and cloud percentage corroborates the winter pattern. The relatively constant wind speed, visibility, and pressure emphasize the overall stability of Santa Rosa's winter climate.

Temperature

December, characterized by an average high temperature of 55.6°F and a low temperature of 41.9°F, is generally the coldest month.

Humidity

The average relative humidity in December is 75%.

Rainfall

In Santa Rosa, during December, the rain falls for 10.5 days and regularly aggregates up to 2.24" of precipitation. Throughout the year, in Santa Rosa, there are 72.8 rainfall days, and 12.01" of precipitation is accumulated.

Daylight

The month with the shortest days in Santa Rosa is December, with an average of 9h and 30min of daylight.
On the first day of the month, sunrise is at 7:09 am and sunset at 4:50 pm. On the last day of December, sunrise is at 7:27 am and sunset at 4:59 pm PST.

Sunshine

December has the least sunshine of the year in Santa Rosa, with an average of 5.7h 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 Santa Rosa. A UV Index reading of 3 to 5 represents a medium vulnerability from unprotected exposure to Sun's UV rays for ordinary individuals.
Note: In December, the UV index of 3 transforms into the following advice:
Be vigilant - Preventing sunburn is recommended. The most potent solar radiation is around mid-day, so one should minimize exposure to direct sunlight during this period. Sunglasses that guard against UVA and UVB rays are pivotal in minimizing sun-induced ocular damage.
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FAQ

What time of the year is the coldest in Santa Rosa?

December, marked by an average high-temperature of 55.6°F and a low-temperature of 41.9°F, is the coldest month.

What are the temperatures in Santa Rosa in December?

December temperatures in Santa Rosa, California, vary between a high-temperature of 55.6°F and a low-temperature of 41.9°F.

What is the average humidity in December in Santa Rosa?

In December, the average relative humidity is 75%.

How many days does it rain in December in Santa Rosa?

In Santa Rosa, in December, during 10.5 rainfall days, 2.24" of precipitation is typically accumulated.

What is the month with the shortest days in Santa Rosa?

With an average of 9h and 30min of daylight, December has the shortest days of the year in Santa Rosa.

How many hours of daylight does Santa Rosa have in December?

In December, the average day length is 9h and 32min.

What time are sunrise and sunset in December in Santa Rosa?

On the first day of December, sunrise is at 7:09 am and sunset at 4:50 pm. On the last day of the month, sunrise is at 7:27 am and sunset at 4:59 pm PST.

What is the month with the least sunshine in Santa Rosa?

The month with the least sunshine in Santa Rosa, California, is December, with an average of 5.7h of sunshine.

How many hours of sunshine does Santa Rosa have in December?

In December, the average sunshine duration in Santa Rosa is 5.7h.

What is the month with the lowest UV index in Santa Rosa?

The months with the lowest UV index in Santa Rosa, California, are January, February, November and December, with an average maximum UV index of 3.

How high is the UV index in December in Santa Rosa?

In December, the average daily maximum UV index in Santa Rosa is 3. A UV Index of 3 to 5 symbolizes a moderate vulnerability from exposure to Sun's UV rays.
Average high temperature
Average low temperature
Average pressure
Average wind speed
Average max. wind speed
Average wind speed gusts
Average humidity
Average rainfall
Average rainfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in December
Santa Rosa, CA

Average temperature in December - Santa Rosa, CA
  • Average high temperature in December: 55.6°F

The warmest month (with the highest average high temperature) is August (79.7°F).
The month with the lowest average high temperature is December (55.6°F).

  • Average low temperature in December: 41.9°F

The months with the highest average low temperature are August and September (54.7°F).
The coldest month (with the lowest average low temperature) is December (41.9°F).

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Average pressure in December
Santa Rosa, CA

Average pressure in December - Santa Rosa, CA
  • Average pressure in December: 30.1"Hg

The month with the highest atmospheric pressure is January (30.13"Hg).
The months with the lowest atmospheric pressure are June, August and September (29.92"Hg).

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Average wind speed in December
Santa Rosa, CA

Average wind speed in December - Santa Rosa, CA
  • Average wind speed in December: 5.2mph

The windiest month (with the highest average wind speed) is May (7.1mph).
The calmest month (with the lowest average wind speed) is November (4.9mph).

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Average humidity in December
Santa Rosa, CA

Average humidity in December - Santa Rosa, CA
  • Average humidity in December: 75%

The month with the highest relative humidity is March (77%).
The month with the lowest relative humidity is September (63%).

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Average rainfall in December
Santa Rosa, CA

Average rainfall in December - Santa Rosa, CA
  • Average rainfall in December: 2.24"

The wettest month (with the highest rainfall) is February (2.64").
The driest months (with the least rainfall) are July and August (0.04").

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Average rainfall days in December
Santa Rosa, CA

Average rainfall days in December - Santa Rosa, CA
  • Average rainfall days in December: 10.5 days

The month with the highest number of rainy days is March (12.6 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
Santa Rosa, CA

Average daylight in December / Average sunshine in December - Santa Rosa, CA
  • Average daylight in December: 9h and 3min

The month with the longest days is June (Average daylight: 14h and 48min).
The month with the shortest days is December (Average daylight: 9h and 30min).

  • Average sunshine in December: 5h and 4min

The month with the most sunshine is July (Average sunshine: 11h and 54min).
The month with the least sunshine is December (Average sunshine: 5h and 42min).

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Average sunshine days in December
Santa Rosa, CA

Average sunshine days in December - Santa Rosa, CA
  • Average sunshine days in December: 19.5 days

The month with the most sunshine days is July (27.2 days).
The month with the least sunshine days is March (17.1 days).

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Average UV index in December
Santa Rosa, CA

Average UV index in December - Santa Rosa, CA
  • Average UV index in December: 3

The month with the highest UV index is June (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 3).

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Average cloud cover in December
Santa Rosa, CA

Average cloud cover in December - Santa Rosa, CA
  • Average cloud cover in December: 37

The month with the most cloud cover is March (Cloud cover 39).
The month with the least cloud cover is July (Cloud cover 9).

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Average visibility in December
Santa Rosa, CA

Average visibility in December - Santa Rosa, CA
  • Average visibility in December: 6mi

The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).

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Santa Rosa, California, USA

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