December weather forecast
O'Brien, CA

Share

Weather in December

December, the first month of the winter in O'Brien, is still a chilly month, with an average temperature ranging between max 47.8°F (8.8°C) and min 33.6°F (0.9°C).

Temperature

December is the coldest month, with the temperature often reaching an average high of 47.8°F (8.8°C) and an average low of 33.6°F (0.9°C).

Humidity

In December, the average relative humidity in O'Brien is 74%.

Rainfall

In O'Brien, in December, it is raining for 12.7 days, with typically 3.5" (89mm) of accumulated precipitation. Throughout the year, there are 102.3 rainfall days, and 24.21" (615mm) of precipitation is accumulated.

Snowfall

Months with snowfall in O'Brien are January through March, November and December. In December, in O'Brien, it is snowing for 1 days. Throughout December, 1.1" (28mm) of snow is accumulated. In O'Brien, during the entire year, snow falls for 4.6 days and aggregates up to 4.45" (113mm) of snow.

Daylight

The month with the shortest days in O'Brien is December, with an average of 9h and 18min of daylight.
On the first day of the month, sunrise is at 7:14 am and sunset at 4:42 pm. On the last day of December, in O'Brien, sunrise is at 7:33 am and sunset at 4:51 pm PST.

Sunshine

With an average of 5.3h of sunshine, December has the least sunshine of the year.

UV index

February, 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 low health risk from exposure to the Sun's UV rays for the average person.
Note: In December, a daily maximum UV index of 2 leads to the following instructions:
Unlike children, who always need sun protection, most individuals can remain in the sun for up to an hour without getting burnt. The Sun is most powerful around mid-day, so it's a good practice to reduce direct exposure. Sun-related eye harm can be minimized with proper sunglasses offering UVA and UVB coverage. Take precaution! The reflection from snow can almost double the UV radiation of the Sun.
[Resources]

Frequently asked questions

What time of the year is the coldest in O'Brien?

O'Brien's December weather reaches an average high of 47.8°F (8.8°C) and an average low of 33.6°F (0.9°C), making it the coldest month.

What is the usual temperature for O'Brien in December?

The high-temperature in O'Brien during December is 47.8°F (8.8°C) and the low-temperature is 33.6°F (0.9°C). In September, the average heat index (a.k.a. 'felt air temperature', 'apparent temperature'), which calculates the temperature value influenced by the moisture in the air, is computed to be 84.2°F (29°C).

What is the average humidity in December in O'Brien?

In December, the average relative humidity in O'Brien, California, is 74%.

How much does it rain in O'Brien in December?

In December, in O'Brien, California, the rain falls for 12.7 days. Throughout December, 3.5" (89mm) of precipitation is accumulated.

How much does it snow in O'Brien in December?

In O'Brien, California, in December, snow falls for 1 days, with typically accumulated 1.1" (28mm) of snow.

What is the month with the shortest days in O'Brien?

The month with the shortest days in O'Brien is December, with an average of 9h and 18min of daylight.

What is the average length of the day in December in O'Brien?

In O'Brien, California, the average day length in December is 9h and 18min.

When are sunrise and sunset in December in O'Brien?

On the first day of December, sunrise is at 7:14 am and sunset at 4:42 pm. On the last day of the month, sunrise is at 7:33 am and sunset at 4:51 pm PST.

What is the month with the least sunshine in O'Brien?

The month with the least sunshine in O'Brien is December, with an average of 5.3h of sunshine.

How many hours of sunshine does O'Brien have in December?

The average sunshine duration in December in O'Brien, California, is 5.3h.

When is the lowest UV index in O'Brien?

February, November and December, with an average maximum UV index of 2, are months with the lowest UV index in O'Brien, California.

How high is the UV index in December in O'Brien?

In O'Brien, California, the average daily maximum UV index in December is 2. A UV Index of 2, and less, symbolizes a low health threat from exposure to the Sun's 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
O'Brien, CA

Average temperature in December - O
  • Average high temperature in December: 47.8°F

The warmest month (with the highest average high temperature) is July (91.6°F).
The month with the lowest average high temperature is December (47.8°F).

  • Average low temperature in December: 33.6°F

The month with the highest average low temperature is July (59.4°F).
The coldest month (with the lowest average low temperature) is December (33.6°F).

[Resources]

Average pressure in December
O'Brien, CA

Average pressure in December - O
  • Average pressure in December: 30.14"Hg

The month with the highest atmospheric pressure is January (30.16"Hg).
The month with the lowest atmospheric pressure is August (29.92"Hg).

[Resources]

Average wind speed in December
O'Brien, CA

Average wind speed in December - O
  • Average wind speed in December: 4.7mph

The windiest months (with the highest average wind speed) are March and October (5.3mph).
The calmest months (with the lowest average wind speed) are August and November (4.5mph).

[Resources]

Average humidity in December
O'Brien, CA

Average humidity in December - O
  • Average humidity in December: 74%

The month with the highest relative humidity is March (77%).
The month with the lowest relative humidity is August (37%).

[Resources]

Average rainfall in December
O'Brien, CA

Average rainfall in December - O
  • Average rainfall in December: 3.5"

The wettest month (with the highest rainfall) is March (4.8").
The driest month (with the least rainfall) is July (0.12").

[Resources]

Average rainfall days in December
O'Brien, CA

Average rainfall days in December - O
  • Average rainfall days in December: 12.7 days

The month with the highest number of rainy days is March (16.8 days).
The month with the least rainy days is August (1.7 days).

[Resources]

Average snowfall in December
O'Brien, CA

Average snowfall in December - O
  • Average snowfall in December: 1.1"

The month with the highest snowfall is November (1.3").
The months with the least snowfall are April, May, June, July, August, September and October (0").

[Resources]

Average snowfall days in December
O'Brien, CA

Average snowfall days in December - O
  • Average snowfall days in December: 1 days

The month with the highest number of snowfall days is February (1.9 days).
The months with the least snowfall days are April, May, June, July, August, September and October (0 days).

[Resources]

Average daylight in December /
Average sunshine in December
O'Brien, CA

Average daylight in December / Average sunshine in December - O
  • 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 12min).
The month with the least sunshine is December (Average sunshine: 5h and 18min).

[Resources]

Average sunshine days in December
O'Brien, CA

Average sunshine days in December - O
  • Average sunshine days in December: 15.7 days

The month with the most sunshine days is August (27.1 days).
The month with the least sunshine days is March (11.8 days).

[Resources]

Average UV index in December
O'Brien, CA

Average UV index in December - O
  • Average UV index in December: 2

The month with the highest UV index is July (UV index 7).
The months with the lowest UV index are February, November and December (UV index 2).

[Resources]

Average cloud cover in December
O'Brien, CA

Average cloud cover in December - O
  • Average cloud cover in December: 41

The month with the most cloud cover is March (Cloud cover 44).
The month with the least cloud cover is August (Cloud cover 5).

[Resources]

Average visibility in December
O'Brien, CA

Average visibility in December - O
  • Average visibility in December: 5mi

The months with the highest visibility are January, February, March, April, May, June, July, August, September, October and November (6mi).
The month with the lowest visibility is December (5mi).

[Resources]

O'Brien, California, USA

Weather forecast for your location

1. Click Locate me button
2. Allow the app to use your location