December weather forecast
Castella, CA

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Weather in December

The first month of the winter, December, is also a wintry month in Castella, California, with an average temperature ranging between min 26.8°F (-2.9°C) and max 41°F (5°C).

Temperature

In Castella, the month of December is known for its lowest average temperatures, reaching a high of 41°F (5°C) and a low of 26.8°F (-2.9°C).

Humidity

The average relative humidity in December is 79%.

Rainfall

In Castella, during December, the rain falls for 13.1 days and regularly aggregates up to 4.96" (126mm) of precipitation. In Castella, during the entire year, the rain falls for 113.4 days and collects up to 31.3" (795mm) of precipitation.

Snowfall

Months with snowfall are January through May, October through December. In December, it is snowing for 6.4 days. Throughout December, 7.36" (187mm) of snow is accumulated. In Castella, during the entire year, snow falls for 28.7 days and aggregates up to 45.51" (1156mm) of snow.

Daylight

The month with the shortest days is December, with an average of 9h and 18min of daylight.
On the first day of the month, sunrise is at 7:15 am and sunset at 4:41 pm. On the last day of December, sunrise is at 7:34 am and sunset at 4:50 pm PST.

Sunshine

December has the least sunshine of the year in Castella, California, with an average of 5.2h of sunshine.

UV index

January through March, 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 low health risk from exposure to the Sun's UV radiation for average individuals.
Note: In December, the maximum UV index of 2 suggests this advice:
While most individuals can withstand prolonged sun exposure, it is imperative that babies, children, and those with sensitive skin always be shielded. Limiting exposure to the direct Sun during midday hours can help prevent harmful UV radiation effects. To best shield against UV radiation, choose sun-safe garments and dependable sunglasses. Guard yourself! Snow reflection can almost double the UV radiation from the Sun.
Updated: Feb 9, 2024 | Published by: Weather U.S. | About Us / Weather Forecasting / Data Sources

Frequently asked questions

What is the coldest month in Castella?

The month of December sees the average lowest temperatures in Castella, reaching 41°F (5°C) at the peak and 26.8°F (-2.9°C) at the low.

How cold is it in Castella in December?

An average high-temperature, in December, in Castella, is 41°F (5°C) and the average low-temperature is 26.8°F (-2.9°C). The average heat index (a.k.a. 'feels like', 'apparent temperature'), which represents the influence of relative humidity on air temperature, in August is appraised at 84.2°F (29°C).

What is the average humidity in December in Castella?

The average relative humidity in December is 79%.

How much does it rain in Castella in December?

In Castella, California, in December, it is raining for 13.1 days, with typically 4.96" (126mm) of accumulated precipitation.

How much does it snow in Castella in December?

In December, it is snowing for 6.4 days. Throughout December, 7.36" (187mm) of snow is accumulated.

What is the month with the shortest days in Castella?

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

How many hours of daylight does Castella have in December?

In Castella, the average day length in December is 9h and 16min.

What time are sunrise and sunset in December in Castella?

On the first day of December in Castella, sunrise is at 7:15 am and sunset at 4:41 pm. On the last day of the month, sunrise is at 7:34 am and sunset at 4:50 pm PST.

What is the month with the least sunshine in Castella?

With an average of 5.2h of sunshine, December has the least sunshine of the year in Castella.

How many hours of sunshine does Castella have in December?

The average sunshine duration in December in Castella, California, is 5.2h.

When is the lowest UV index in Castella?

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

How high is the UV index in December in Castella?

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

Average temperature in December - Castella, CA
  • Average high temperature in December: 41°F

The warmest month (with the highest average high temperature) is July (85.6°F).
The month with the lowest average high temperature is December (41°F).

  • Average low temperature in December: 26.8°F

The months with the highest average low temperature are July and August (51.4°F).
The coldest month (with the lowest average low temperature) is December (26.8°F).

Average pressure in December
Castella, CA

Average pressure in December - Castella, CA
  • Average pressure in December: 30.15"Hg

The month with the highest atmospheric pressure is January (30.17"Hg).
The month with the lowest atmospheric pressure is August (29.93"Hg).

Average wind speed in December
Castella, CA

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

The windiest month (with the highest average wind speed) is March (5.7mph).
The calmest month (with the lowest average wind speed) is August (4.1mph).

Average humidity in December
Castella, CA

Average humidity in December - Castella, CA
  • Average humidity in December: 79%

The month with the highest relative humidity is March (81%).
The month with the lowest relative humidity is August (44%).

Average rainfall in December
Castella, CA

Average rainfall in December - Castella, CA
  • Average rainfall in December: 4.96"

The wettest month (with the highest rainfall) is March (5.55").
The driest month (with the least rainfall) is July (0.24").

Average rainfall days in December
Castella, CA

Average rainfall days in December - Castella, CA
  • Average rainfall days in December: 13.1 days

The month with the highest number of rainy days is March (17.3 days).
The month with the least rainy days is August (2.7 days).

Average snowfall in December
Castella, CA

Average snowfall in December - Castella, CA
  • Average snowfall in December: 7.36"

The month with the highest snowfall is January (12.6").
The months with the least snowfall are June, July, August and September (0").

Average snowfall days in December
Castella, CA

Average snowfall days in December - Castella, CA
  • Average snowfall days in December: 6.4 days

The month with the highest number of snowfall days is December (6.4 days).
The months with the least snowfall days are June, July and August (0 days).

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

Average daylight in December / Average sunshine in December - Castella, CA
  • 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 1min

The month with the most sunshine is July (Average sunshine: 12h and 6min).
The month with the least sunshine is December (Average sunshine: 5h and 12min).

Average sunshine days in December
Castella, CA

Average sunshine days in December - Castella, CA
  • Average sunshine days in December: 13.9 days

The month with the most sunshine days is August (25.7 days).
The month with the least sunshine days is March (11.1 days).

Average UV index in December
Castella, CA

Average UV index in December - Castella, CA
  • Average UV index in December: 2

The months with the highest UV index are June and July (UV index 6).
The months with the lowest UV index are January, February, March, November and December (UV index 2).

Average cloud cover in December
Castella, CA

Average cloud cover in December - Castella, CA
  • Average cloud cover in December: 44

The month with the most cloud cover is March (Cloud cover 47).
The month with the least cloud cover is August (Cloud cover 6).

Average visibility in December
Castella, CA

Average visibility in December - Castella, CA
  • Average visibility in December: 5mi

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

Castella, California, USA

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