January weather forecast
Sonoma, CA

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

Weather in January

Kicking off the year in Sonoma, California, the weather in January ushers in mild winter temperatures. The days tend to be cooler, leading to a chilly ambiance. Weather patterns fluctuate frequently with a larger portion of the month shrouded in cloud cover. Significant rainfall can be expected, with January recording one of the highest amounts. Despite the cooler climate and ample cloud cover, daylight persists for approximately 9.9 hours daily.

Temperature

Sonoma, California, greets January with an average high-temperature of a refreshing 56.3°F (13.5°C), marking a slight deviation from the preceding month. During January, Sonoma experiences a consistent low-temperature average of 42.1°F (5.6°C).

Humidity

In Sonoma, the average relative humidity in January is 74%.

Rainfall

In Sonoma, during January, the rain falls for 10.4 days and regularly aggregates up to 2.87" (73mm) of precipitation. Throughout the year, there are 73.3 rainfall days, and 15.47" (393mm) of precipitation is accumulated.

Daylight

In Sonoma, the average length of the day in January is 9h and 52min.
On the first day of the month, sunrise is at 7:26 am and sunset at 5:00 pm. On the last day of January, sunrise is at 7:15 am and sunset at 5:30 pm PST.

Sunshine

In January, the average sunshine is 5.7h.

UV index

The months with the lowest UV index are January, February, November and December, with an average maximum UV index of 3. A UV Index reading of 3 to 5 represents a medium health hazard from unsafe exposure to UV radiation for the average person.
Note: A daily maximum UV index of 3 in January translates into the following instructions:
Make use of precautions - Shielding skin and eyes from injury is a requirement. The intensity of the Sun's UV radiation during midday suggests reducing time spent outdoors. On bright days sunglasses that block both UVA and UVB rays should be worn. A hat with a wide brim is extremely helpful, as it can prevent roughly 50% of UV radiation from reaching the eyes.
Updated: Jul 17, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What is the temperature in January?

During January, Sonoma experiences an average high-temperature of 56.3°F (13.5°C) and a low-temperature of 42.1°F (5.6°C).

What is the average humidity in January?

The average relative humidity in January in Sonoma is 74%.

How many days does it rain in January?

In January, the rain falls for 10.4 days. Throughout January, 2.87" (73mm) of precipitation is accumulated.

How many hours of daylight does Sonoma have in January?

In Sonoma, California, the average day length in January is 9h and 52min.

When is the sunrise / sunset in January?

In January, on the first day of the month, sunrise is at 7:26 am and sunset at 5:00 pm. On the last day of the month, sunrise is at 7:15 am and sunset at 5:30 pm PST.

How long on average sun shines in January in Sonoma?

The average sunshine duration in January is 5.7h.

What are the months with the lowest UV index?

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

What is the UV index intensity in January?

In Sonoma, California, the average daily maximum UV index in January is 3. A UV Index value of 3 to 5 symbolizes a medium hazard to health from unsafe exposure to Sun's UV rays.
Average humidity
Average rainfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in January
Sonoma, CA

Average temperature in January - Sonoma, CA
  • Average high temperature in January: 56.3°F

The warmest month (with the highest average high temperature) is August (82.9°F).
The month with the lowest average high temperature is December (55°F).

  • Average low temperature in January: 42.1°F

The month with the highest average low temperature is August (54.9°F).
The coldest month (with the lowest average low temperature) is December (41.4°F).

Average pressure in January
Sonoma, CA

Average pressure in January - Sonoma, CA
  • Average pressure in January: 30.13"Hg

The month with the highest atmospheric pressure is January (30.13"Hg).
The month with the lowest atmospheric pressure is June (29.91"Hg).

Average wind speed in January
Sonoma, CA

Average wind speed in January - Sonoma, CA
  • Average wind speed in January: 4.8mph

The windiest month (with the highest average wind speed) is May (6.2mph).
The calmest month (with the lowest average wind speed) is November (4.4mph).

Average humidity in January
Sonoma, CA

Average humidity in January - Sonoma, CA
  • Average humidity in January: 74%

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

Average rainfall in January
Sonoma, CA

Average rainfall in January - Sonoma, CA
  • Average rainfall in January: 2.87"

The wettest month (with the highest rainfall) is February (3.43").
The driest months (with the least rainfall) are July and August (0.04").

Average rainfall days in January
Sonoma, CA

Average rainfall days in January - Sonoma, CA
  • Average rainfall days in January: 10.4 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).

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

Average daylight in January / Average sunshine in January - Sonoma, CA
  • Average daylight in January: 9h and 5min

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 36min).

  • Average sunshine in January: 5h and 4min

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 36min).

Average sunshine days in January
Sonoma, CA

Average sunshine days in January - Sonoma, CA
  • Average sunshine days in January: 19.9 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).

Average UV index in January
Sonoma, CA

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

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

Average cloud cover in January
Sonoma, CA

Average cloud cover in January - Sonoma, CA
  • Average cloud cover in January: 37

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

Average visibility in January
Sonoma, CA

Average visibility in January - Sonoma, CA
  • Average visibility in January: 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).

Sonoma, California, USA

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