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

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

Temperature

December is Clearlake's coldest month, registering average high temperatures of 52.7°F (11.5°C) and lows of 38.1°F (3.4°C).

Humidity

The average relative humidity in December is 72%.

Rainfall

In Clearlake, during December, the rain falls for 11.2 days and regularly aggregates up to 3.11" (79mm) of precipitation. Throughout the year, there are 79.8 rainfall days, and 17.44" (443mm) of precipitation is accumulated.

Snowfall

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

Sunshine

The month with the least sunshine 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. A UV Index value of 2, and less, symbolizes a minimal health vulnerability from unsafe exposure to UV radiation for the ordinary person.
Note: In December, the maximum UV index of 2 transforms into these recommendations:
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. Avoiding direct sun during mid-day hours can prevent harmful UV radiation exposure. To mitigate harm from sun exposure, pick sunglasses offering UVA and UVB defense. Mark this! Snow reflection can nearly double the UV radiation intensity from the Sun.

Frequently asked questions

What part of the year is the coldest?

During the coldest month in Clearlake, December, temperatures average a high of 52.7°F (11.5°C) and a low of 38.1°F (3.4°C).

What is the usual temperature for Clearlake in December?

The high-temperature in Clearlake, California, during December is 52.7°F (11.5°C) and the low-temperature is 38.1°F (3.4°C). The average heat index (a.k.a. 'felt air temperature', 'feels like'), which combines air temperature and relative humidity, in September is estimated at 86°F (30°C).

What is the average humidity in December in Clearlake?

In Clearlake, the average relative humidity in December is 72%.

How many days does it rain in December?

In December, the rain falls for 11.2 days. Throughout December, 3.11" (79mm) of precipitation is accumulated.

How many days does it snow in December?

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?

December has the shortest days of the year, with an average of 9h and 30min of daylight.

What is the average length of the day in December?

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

When is the sunrise / sunset in December?

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, sunrise is at 7:29 am and sunset at 4:58 pm PST.

What is the month with the least sunshine in Clearlake?

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

How long on average sun shines in December?

In Clearlake, the average sunshine duration in December is 5.3h.

What is the month with the lowest UV index?

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

What is the UV index intensity in December?

The average daily maximum UV index in December is 2. A UV Index of 2, and less, symbolizes a minimal health vulnerability 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).

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).

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).

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%).

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").

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).

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").

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).

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).

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).

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).

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).

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).

Clearlake, California, USA

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