December weather forecast
Castaic, CA

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Weather in December

December, the first month of the winter in Castaic, is still a mild month, with temperature in the range of an average low of 42.3°F (5.7°C) and an average high of 59.5°F (15.3°C).

Temperature

In Castaic, the lowest temperatures are generally noted in December, averaging a high of 59.5°F (15.3°C) and a low of 42.3°F (5.7°C).

Humidity

The average relative humidity in December is 52%.

Rainfall

December is the month with the most rainfall. Rain falls for 5.3 days and accumulates 1.42" (36mm) of precipitation.

Daylight

December has the shortest days of the year, with an average of 9h and 54min of daylight.
On the first day of the month, sunrise is at 6:43 am and sunset at 4:44 pm. On the last day of December, in Castaic, sunrise is at 7:01 am and sunset at 4:54 pm PST.

Sunshine

The average sunshine in December in Castaic is 6.8h.

UV index

The months with the lowest UV index are February, November and December, with an average maximum UV index of 3. A UV Index of 3 to 5 symbolizes a moderate threat to health from unsafe exposure to UV radiation for average individuals.
Note: The daily high UV index of 3 in December translates into this advice:
Take necessary precautions - Protection from skin and eye injury is mandatory. Limiting sun exposure during midday hours helps in reducing the harmful effects of UV radiation. Employ a wide-brim hat for potent defense against up to 50% of UV rays.
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Frequently asked questions

What are the coldest months in Castaic?

Castaic's coldest month, December, registers temperatures that range from a high of 59.5°F (15.3°C) to a low of 42.3°F (5.7°C).

What are the temperatures in Castaic in December?

December temperatures vary between a high-temperature of 59.5°F (15.3°C) and a low-temperature of 42.3°F (5.7°C). The average heat index (a.k.a. 'felt air temperature', 'feels like'), which represents the influence of relative humidity on air temperature, in September is estimated at 84.2°F (29°C).

What is the average humidity in December in Castaic?

The average relative humidity in December is 52%.

What is the rainiest month in Castaic?

December is the month with the most rainfall. Rain falls for 5.3 days and accumulates 1.42" (36mm) of precipitation.

How many days does it rain in December in Castaic?

In Castaic, in December, during 5.3 rainfall days, 1.42" (36mm) of precipitation is typically accumulated.

What is the month with the shortest days in Castaic?

The month with the shortest days in Castaic, California, is December, with an average of 9h and 54min of daylight.

How many hours of daylight does Castaic have in December?

The average day length in December in Castaic is 9h and 53min.

What time are sunrise and sunset in December in Castaic?

In December, on the first day of the month, sunrise is at 6:43 am and sunset at 4:44 pm. On the last day of the month, in Castaic, sunrise is at 7:01 am and sunset at 4:54 pm PST.

How long on average sun shines in December in Castaic?

The average sunshine duration in December in Castaic, California, is 6.8h.

What is the month with the lowest UV index in Castaic?

February, November and December, with an average maximum UV index of 3, are months with the lowest UV index.

How high is the UV index in December in Castaic?

In December, the average daily maximum UV index in Castaic is 3. A UV Index reading of 3 to 5 represents a medium health risk from exposure to Sun's UV rays.
Average humidity
Average rainfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in December
Castaic, CA

Average temperature in December - Castaic, CA
  • Average high temperature in December: 59.5°F

The warmest month (with the highest average high temperature) is August (88.2°F).
The month with the lowest average high temperature is December (59.5°F).

  • Average low temperature in December: 42.3°F

The month with the highest average low temperature is August (63.7°F).
The coldest month (with the lowest average low temperature) is December (42.3°F).

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Average pressure in December
Castaic, CA

Average pressure in December - Castaic, CA
  • Average pressure in December: 30.08"Hg

The month with the highest atmospheric pressure is January (30.11"Hg).
The month with the lowest atmospheric pressure is June (29.88"Hg).

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Average wind speed in December
Castaic, CA

Average wind speed in December - Castaic, CA
  • Average wind speed in December: 7.3mph

The windiest months (with the highest average wind speed) are January and December (7.3mph).
The calmest month (with the lowest average wind speed) is August (4.9mph).

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Average humidity in December
Castaic, CA

Average humidity in December - Castaic, CA
  • Average humidity in December: 52%

The month with the highest relative humidity is March (56%).
The months with the lowest relative humidity are August and October (43%).

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Average rainfall in December
Castaic, CA

Average rainfall in December - Castaic, CA
  • Average rainfall in December: 1.42"

The wettest month (with the highest rainfall) is December (1.42").
The driest months (with the least rainfall) are June and August (0.04").

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Average rainfall days in December
Castaic, CA

Average rainfall days in December - Castaic, CA
  • Average rainfall days in December: 5.3 days

The month with the highest number of rainy days is March (6.9 days).
The month with the least rainy days is June (0.7 days).

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

Average daylight in December / Average sunshine in December - Castaic, CA
  • Average daylight in December: 9h and 5min

The month with the longest days is June (Average daylight: 14h and 24min).
The month with the shortest days is December (Average daylight: 9h and 54min).

  • Average sunshine in December: 6h and 5min

The months with the most sunshine are June and July (Average sunshine: 12h and 6min).
The month with the least sunshine is February (Average sunshine: 6h and 42min).

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Average sunshine days in December
Castaic, CA

Average sunshine days in December - Castaic, CA
  • Average sunshine days in December: 24.9 days

The month with the most sunshine days is August (28.7 days).
The month with the least sunshine days is February (21.5 days).

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Average UV index in December
Castaic, CA

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

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

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Average cloud cover in December
Castaic, CA

Average cloud cover in December - Castaic, CA
  • Average cloud cover in December: 22

The month with the most cloud cover is March (Cloud cover 23).
The month with the least cloud cover is August (Cloud cover 4).

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Average visibility in December
Castaic, CA

Average visibility in December - Castaic, 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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Castaic, California, USA

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