December weather forecast and climate
O'Brien, CA

Weather in December

The first month of the winter, December, is also a frosty month in O'Brien, California, with average temperature fluctuating between 33.6°F (0.9°C) and 47.8°F (8.8°C).

Temperature

The coldest month is December, with an average high-temperature of 47.8°F (8.8°C) and an average low-temperature 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. In O'Brien, during the entire year, the rain falls for 102.3 days and collects up to 24.21" (615mm) of precipitation.

Snowfall

Months with snowfall 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, California, during the entire year, snow falls for 4.6 days, and aggregates up to 4.45" (113mm) of snow.

Daylight

December has the shortest days of the year, with an average of 9.3h of daylight.

Sunshine

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

UV index

Months with the lowest UV index are February, November and December, with an average maximum UV index of 2. A UV Index reading of 2, and below, represents a low health risk from the exposure to the Sun's UV rays for ordinary individuals.
Note: The daily maximum UV index of 2 interpret into the following advice:
Most people can stay in the Sun for up to 1 hour without burning, apart from children that always must be protected from sun exposure. The Sun's most intense and consequently most harmful UV radiation during midday hours should be decreased by minimizing exposure and seeking shade. 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. Caution! The reflection of snow can nearly double the intensity of the Sun's UV radiation.
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FAQ

What is the coldest month in O'Brien?

The coldest month in O'Brien, California, is December, with an average high-temperature of 47.8°F (8.8°C) and an average low-temperature of 33.6°F (0.9°C).

What is the temperature in December in O'Brien?

The average high-temperature, in December, in O'Brien, is 47.8°F (8.8°C), while the average low-temperature is 33.6°F (0.9°C).

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

In December, the average relative humidity is 74%.

How many days does it rain in December in O'Brien?

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

How many days does it snow in December in O'Brien?

In December, in O'Brien, it is snowing for 1 days. Throughout December, 1.1" (28mm) of snow is accumulated.

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

December has the shortest days of the year in O'Brien, with an average of 9.3h of daylight.

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

The average length of the day in December in O'Brien, California, is 9.3h.

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

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

How long on average sun shines in December in O'Brien?

The average sunshine in December 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.

What is the UV index reading in December in O'Brien?

In O'Brien, the average daily maximum UV index in December is 2. A UV Index reading of 2, and below, represents a minimal health vulnerability from the exposure to the Sun's UV rays.

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).

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Average pressure in December
O'Brien, CA

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

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

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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).

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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%).

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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").

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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).

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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").
Months with the least snowfall are April, May, June, July, August, September and October (0").

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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).
Months with the least snowfall days are April, May, June, July, August, September and October (0 days).

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

Average daylight in December / Average sunshine in December - O
  • Average daylight in December: 9.3h

The month with the longest days is June (Average daylight: 15.1h).
The month with the shortest days is December (Average daylight: 9.3h).

  • Average sunshine in December: 5.3h

The month with the most sunshine is July (Average sunshine: 12.2h).
The month with the least sunshine is December (Average sunshine: 5.3h).

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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).

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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).
Months with the lowest UV index are February, November and December (UV index 2).

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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).

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Average visibility in December
O'Brien, CA

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

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).

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