December weather forecast and climate
Diablo, CA

Weather in December

The first month of the winter, December, is also a moderate month in Diablo, California, with average temperature varying between 42.3°F (5.7°C) and 55.8°F (13.2°C).

Temperature

With an average high-temperature of 55.8°F (13.2°C) and an average low-temperature of 42.3°F (5.7°C), December is the coldest month.

Humidity

The average relative humidity in December is 71%.

Rainfall

In December, the rain falls for 9.8 days. Throughout December, 1.73" (44mm) of precipitation is accumulated. In Diablo, during the entire year, the rain falls for 65.6 days and collects up to 11.22" (285mm) of precipitation.

Daylight

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

Sunshine

December has the least sunshine of the year, with an average of 5.8h of sunshine.

UV index

Months with the lowest UV index are January, February, November and December, with an average maximum UV index of 3. A UV Index estimate of 3 to 5 represents a medium health hazard from unsafe exposure to the UV radiation for average individuals.
Note: In December, the average maximum UV index of 3 translate into the following recommendations:
Take precautions - Protection against sunburn is recommended. The Sun's most intense and consequently most harmful UV radiation during midday hours should be decreased by minimizing exposure and seeking shade. 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.
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FAQ

What is the coldest month in Diablo?

With an average high-temperature of 55.8°F (13.2°C) and an average low-temperature of 42.3°F (5.7°C), December is the coldest month in Diablo, California.

What is the temperature in December in Diablo?

In December, the average high-temperature is 55.8°F (13.2°C), and the average low-temperature is 42.3°F (5.7°C).

What is the average humidity in December in Diablo?

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

How much does it rain in Diablo in December?

In Diablo, in December, during 9.8 rainfall days, 1.73" (44mm) of precipitation is typically accumulated.

What is the month with the shortest days in Diablo?

The month with the shortest days in Diablo is December, with an average of 9.6h of daylight.

How many hours of daylight does Diablo have in December?

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

What is the month with the least sunshine in Diablo?

December has the least sunshine of the year in Diablo, with an average of 5.8h of sunshine.

How long on average sun shines in December in Diablo?

The average sunshine in December in Diablo is 5.8h.

What are the months with the lowest UV index in Diablo?

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 December in Diablo?

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

Average temperature in December
Diablo, CA

Average temperature in December - Diablo, CA
  • Average high temperature in December: 55.8°F

The warmest month (with the highest average high temperature) is July (83.8°F).
The month with the lowest average high temperature is December (55.8°F).

  • Average low temperature in December: 42.3°F

Months with the highest average low temperature are August and September (56.7°F).
The coldest month (with the lowest average low temperature) is January (42.1°F).

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Average pressure in December
Diablo, CA

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

The month with the highest atmospheric pressure is January (30.14").
Months with the lowest atmospheric pressure are June, August and September (29.92").

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Average wind speed in December
Diablo, CA

Average wind speed in December - Diablo, CA
  • Average wind speed in December: 4.8mph

The windiest month (with the highest average wind speed) is May (6.9mph).
The calmest month (with the lowest average wind speed) is November (4.3mph).

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Average humidity in December
Diablo, CA

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

The month with the highest relative humidity is March (74%).
The month with the lowest relative humidity is September (57%).

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Average rainfall in December
Diablo, CA

Average rainfall in December - Diablo, CA
  • Average rainfall in December: 1.73"

The wettest month (with the highest rainfall) is February (2.36").
The driest months (with the least rainfall) are July and August (0").

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Average rainfall days in December
Diablo, CA

Average rainfall days in December - Diablo, CA
  • Average rainfall days in December: 9.8 days

The month with the highest number of rainy days is March (12.6 days).
The month with the least rainy days is August (0.6 days).

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

Average daylight in December / Average sunshine in December - Diablo, 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: 5.8h

The month with the most sunshine is July (Average sunshine: 12.1h).
The month with the least sunshine is December (Average sunshine: 5.8h).

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Average sunshine days in December
Diablo, CA

Average sunshine days in December - Diablo, CA
  • Average sunshine days in December: 20.6 days

The month with the most sunshine days is July (30.2 days).
The month with the least sunshine days is March (17.6 days).

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Average UV index in December
Diablo, CA

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

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

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Average cloud cover in December
Diablo, CA

Average cloud cover in December - Diablo, CA
  • Average cloud cover in December: 35

The month with the most cloud cover is March (Cloud cover 36).
The month with the least cloud cover is July (Cloud cover 6).

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Average visibility in December
Diablo, CA

Average visibility in December - Diablo, 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).

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