December weather forecast
Clearlake, CA

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A long footbridge over the marina in Clearlake, California
A long footbridge over the marina in Clearlake, California

Weather in December

December, the first month of the winter in Clearlake, is still a cool month, with an average temperature ranging between min 38.1°F (3.4°C) and max 52.7°F (11.5°C).

Temperature

December is the coldest month, with the temperature often reaching an average high of 52.7°F (11.5°C) and an average low of 38.1°F (3.4°C).

Humidity

The average relative humidity in December is 72%.

Rainfall

In Clearlake, in December, it is raining for 11.2 days, with typically 3.11" (79mm) of accumulated precipitation. In Clearlake, during the entire year, the rain falls for 79.8 days and collects up to 17.44" (443mm) of precipitation.

Snowfall

Months with snowfall in Clearlake are January through March, November and December. In December, it is snowing for 0.2 days. Throughout December, 0.08" (2mm) of snow is accumulated. In Clearlake, during the entire year, snow falls for 1.8 days and aggregates up to 0.98" (25mm) of snow.

Daylight

The month with the shortest days in Clearlake is December, with an average of 9h and 30min of daylight.
On the first day of the month, sunrise is at 7:10 am and sunset at 4:48 pm. On the last day of December, in Clearlake, California, sunrise is at 7:29 am and sunset at 4:58 pm PST.

Sunshine

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

UV index

November and December, with an average maximum UV index of 2, are months with the lowest UV index in Clearlake, California. A UV Index reading of 2, and below, represents a minimal health vulnerability from unprotected exposure to Sun's UV rays for the average person.
Note: A maximum high UV index of 2 in December translates into the following recommendations:
Those with sensitive skin, infants, and children require constant safeguarding from prolonged sun exposure. Direct exposure to the Sun's intense radiation around midday should be avoided for health reasons. For optimum UV protection, wear sun-resistant attire complemented with a hat and quality shades. Note well! The intensity of the Sun's UV rays can be nearly doubled by snow reflection.
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Frequently asked questions

What part of the year is the coldest in Clearlake?

Temperature readings in Clearlake reach their annual highs in December, averaging 52.7°F (11.5°C) and a minimum average of 38.1°F (3.4°C).

What are December temperatures in Clearlake?

The high-temperature, in December, in Clearlake, records 52.7°F (11.5°C), while the low-temperature is 38.1°F (3.4°C). The average heat index (a.k.a. 'real feel', 'felt air temperature'), which takes the relative humidity and factors it into the air temperature reading, in September is calculated to be 86°F (30°C).

What is the average humidity in December in Clearlake?

The average relative humidity in December in Clearlake is 72%.

How many days does it rain in December in Clearlake?

In Clearlake, in December, during 11.2 rainfall days, 3.11" (79mm) of precipitation is typically accumulated.

How many days does it snow in December in Clearlake?

In Clearlake, during December, snow falls for 0.2 days and regularly aggregates up to 0.08" (2mm) of snow.

What is the month with the shortest days in Clearlake?

The month with the shortest days is December, with an average of 9h and 30min of daylight.

How many hours of daylight does Clearlake have in December?

In December, the average day length in Clearlake, California, is 9h and 29min.

When are sunrise and sunset in December in Clearlake?

In December, on the first day of the month, sunrise is at 7:10 am and sunset at 4:48 pm. On the last day of the month, in Clearlake, sunrise is at 7:29 am and sunset at 4:58 pm PST.

What is the month with the least sunshine in Clearlake?

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

How many hours of sunshine does Clearlake have in December?

The average sunshine duration in December is 5.3h.

When is the lowest UV index in Clearlake?

November and December, with an average maximum UV index of 2, are months with the lowest UV index.

What is the UV index reading in December in Clearlake?

The average daily maximum UV index in December in Clearlake, California, is 2. A UV Index estimate of 2, and below, represents 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
Clearlake, CA

Average temperature in December - Clearlake, CA
  • Average high temperature in December: 52.7°F

The warmest month (with the highest average high temperature) is July (91.2°F).
The month with the lowest average high temperature is December (52.7°F).

  • Average low temperature in December: 38.1°F

The month with the highest average low temperature is July (58.8°F).
The coldest month (with the lowest average low temperature) is December (38.1°F).

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Average pressure in December
Clearlake, CA

Average pressure in December - Clearlake, CA
  • Average pressure in December: 30.11"Hg

The month with the highest atmospheric pressure is January (30.14"Hg).
The months with the lowest atmospheric pressure are June and August (29.91"Hg).

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Average wind speed in December
Clearlake, CA

Average wind speed in December - Clearlake, CA
  • Average wind speed in December: 4.7mph

The windiest month (with the highest average wind speed) is April (5.7mph).
The calmest month (with the lowest average wind speed) is November (4.3mph).

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Average humidity in December
Clearlake, CA

Average humidity in December - Clearlake, CA
  • Average humidity in December: 72%

The month with the highest relative humidity is March (74%).
The month with the lowest relative humidity is July (44%).

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Average rainfall in December
Clearlake, CA

Average rainfall in December - Clearlake, CA
  • Average rainfall in December: 3.11"

The wettest month (with the highest rainfall) is February (3.7").
The driest months (with the least rainfall) are July and August (0.04").

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Average rainfall days in December
Clearlake, CA

Average rainfall days in December - Clearlake, CA
  • Average rainfall days in December: 11.2 days

The month with the highest number of rainy days is March (13.9 days).
The months with the least rainy days are July and August (1.1 days).

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Average snowfall in December
Clearlake, CA

Average snowfall in December - Clearlake, CA
  • Average snowfall in December: 0.08"

The month with the highest snowfall is February (0.51").
The months with the least snowfall are April, May, June, July, August, September and October (0").

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Average snowfall days in December
Clearlake, CA

Average snowfall days in December - Clearlake, CA
  • Average snowfall days in December: 0.2 days

The month with the highest number of snowfall days is February (0.9 days).
The 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
Clearlake, CA

Average daylight in December / Average sunshine in December - Clearlake, CA
  • Average daylight in December: 9h and 3min

The month with the longest days is June (Average daylight: 14h and 54min).
The month with the shortest days is December (Average daylight: 9h and 30min).

  • Average sunshine in December: 5h and 2min

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 18min).

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Average sunshine days in December
Clearlake, CA

Average sunshine days in December - Clearlake, CA
  • Average sunshine days in December: 19 days

The month with the most sunshine days is July (29.4 days).
The month with the least sunshine days is March (15.8 days).

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Average UV index in December
Clearlake, CA

Average UV index in December - Clearlake, CA
  • 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 November and December (UV index 2).

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Average cloud cover in December
Clearlake, CA

Average cloud cover in December - Clearlake, CA
  • Average cloud cover in December: 41

The month with the most cloud cover is March (Cloud cover 43).
The month with the least cloud cover is July (Cloud cover 4).

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Average visibility in December
Clearlake, CA

Average visibility in December - Clearlake, CA
  • Average visibility in December: 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).

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Clearlake, California, USA

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