December weather forecast and climate
Vallejo, CA

A colorful orange sunset skyline seen over the Napa River and Bridge in Vallejo, California
A colorful orange sunset skyline seen over the Napa River and Bridge in Vallejo, California

Weather in December

December, the first month of the winter, in Vallejo, is also a moderate month, with average temperature ranging between max 55.4°F (13°C) and min 43.2°F (6.2°C).

Temperature

December is the coldest month, with an average high-temperature of 55.4°F (13°C) and an average low-temperature of 43.2°F (6.2°C).

Humidity

In December, the average relative humidity in Vallejo is 71%.

Rainfall

In December, the rain falls for 8.5 days. Throughout December, 0.79" (20mm) of precipitation is accumulated. Throughout the year, in Vallejo, California, there are 56.9 rainfall days, and 4.88" (124mm) of precipitation is accumulated.

Daylight

December has the shortest days of the year in Vallejo, California, with an average of 9.6h of daylight.

Sunshine

With an average of 5.7h of sunshine, December has the least sunshine of the year in Vallejo, California.

UV index

January, February, November and December, with an average maximum UV index of 3, are months with the lowest UV index. A UV Index value of 3 to 5 symbolizes a medium vulnerability from the exposure to the Sun's UV rays for average individuals.
Note: The average daily UV index of 3 transform into the following instructions:
Take precautions. Light skin individuals may get burned in less than 30 minutes. The solar radiation is most powerful near the mid-day, so the exposure to the direct Sun should be reduced accordingly. A wide-brim hat offers excellent sun protection for eyes, ears, face, and neck. Sunglasses with UVA and UVB protection significantly reduce eye damage from sun exposure. Tightly woven, loose-fitting clothes provide additional protection from the Sun.
[Resources]

FAQ

What is the coldest month in Vallejo?

With an average high-temperature of 55.4°F (13°C) and an average low-temperature of 43.2°F (6.2°C), December is the coldest month in Vallejo.

What is the average humidity in December in Vallejo?

The average relative humidity in December is 71%.

How many days does it rain in December in Vallejo?

In Vallejo, in December, during 8.5 rainfall days, 0.79" (20mm) of precipitation is typically accumulated.

What is the month with the shortest days in Vallejo?

With an average of 9.6h of daylight, December has the shortest days of the year in Vallejo, California.

How many hours of daylight does Vallejo have in December?

In December, the average length of the day in Vallejo is 9.6h.

What is the month with the least sunshine in Vallejo?

December has the least sunshine of the year in Vallejo, California, with an average of 5.7h of sunshine.

How long on average sun shines in December in Vallejo?

In Vallejo, California, the average sunshine in December is 5.7h.

When is the lowest UV index in Vallejo?

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

How high is the UV index in December in Vallejo?

In Vallejo, the average daily maximum UV index in December is 3. A UV Index of 3 to 5 symbolizes a medium health risk from the exposure to the Sun's UV rays.

Average temperature in December
Vallejo, CA

Average temperature in December - Vallejo, CA
  • Average high temperature in December: 55.4°F

The warmest months (with the highest average high temperature) are July and September (80.1°F).
The month with the lowest average high temperature is December (55.4°F).

  • Average low temperature in December: 43.2°F

The month with the highest average low temperature is August (56.5°F).
The coldest month (with the lowest average low temperature) is January (43°F).

[Resources]

Average pressure in December
Vallejo, CA

Average pressure in December - Vallejo, CA
  • Average pressure in December: 30.11"

The month with the highest atmospheric pressure is January (30.14").
The month with the lowest atmospheric pressure is June (29.91").

[Resources]

Average wind speed in December
Vallejo, CA

Average wind speed in December - Vallejo, 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 (4.6mph).

[Resources]

Average humidity in December
Vallejo, CA

Average humidity in December - Vallejo, CA
  • Average humidity in December: 71%

The month with the highest relative humidity is March (75%).
Months with the lowest relative humidity are September and October (60%).

[Resources]

Average rainfall in December
Vallejo, CA

Average rainfall in December - Vallejo, CA
  • Average rainfall in December: 0.79"

The wettest month (with the highest rainfall) is February (1.14").
The driest months (with the least rainfall) are July and August (0.04").

[Resources]

Average rainfall days in December
Vallejo, CA

Average rainfall days in December - Vallejo, CA
  • Average rainfall days in December: 8.5 days

The month with the highest number of rainy days is March (10.2 days).
The month with the least rainy days is August (0.9 days).

[Resources]

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

Average daylight in December / Average sunshine in December - Vallejo, CA
  • Average daylight in December: 9.6h

The month with the longest days is June (Average daylight: 14.8h).
The month with the shortest days is December (Average daylight: 9.6h).

  • Average sunshine in December: 5.7h

The month with the most sunshine is July (Average sunshine: 12h).
The month with the least sunshine is December (Average sunshine: 5.7h).

[Resources]

Average sunshine days in December
Vallejo, CA

Average sunshine days in December - Vallejo, CA
  • Average sunshine days in December: 20.8 days

The month with the most sunshine days is July (27.2 days).
The month with the least sunshine days is March (18.8 days).

[Resources]

Average UV index in December
Vallejo, CA

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

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

[Resources]

Average cloud cover in December
Vallejo, CA

Average cloud cover in December - Vallejo, CA
  • Average cloud cover in December: 36

The month with the most cloud cover is March (Cloud cover 37).
The month with the least cloud cover is July (Cloud cover 9).

[Resources]

Average visibility in December
Vallejo, CA

Average visibility in December - Vallejo, CA
  • Average visibility in December: 6mi

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

[Resources]

Weather forecast for your location

1. Click Locate me button
2. Allow the app to use your location
* you will be automatically redirected to the weather forecast for your location