December weather forecast and climate
Fullerton, CA

Trees and neat lawns of the famous Muckenthaler Community Center in Fullerton, California
Trees and neat lawns of the famous Muckenthaler Community Center in Fullerton, California

Weather in December

December, the first month of the winter, in Fullerton, is also an enjoyable month, with average temperature ranging between max 64°F (17.8°C) and min 50.9°F (10.5°C).

Temperature

With an average high-temperature of 64°F (17.8°C) and an average low-temperature of 50.9°F (10.5°C), December is the coldest month.

Humidity

In December, the average relative humidity in Fullerton is 55%.

Rainfall

The month with the most rainfall in Fullerton is December when the rain falls for 6.6 days and typically aggregates up to 1.54" (39mm) of precipitation.

Daylight

The month with the shortest days in Fullerton, California, is December, with an average of 9.9h of daylight.

Sunshine

With an average of 6.7h of sunshine, December has the least sunshine of the year in Fullerton.

UV index

Months with the lowest UV index are January, February, November and December, with an average maximum UV index of 4. A UV Index reading of 3 to 5 represents a medium health hazard from unprotected exposure to the Sun's UV rays for ordinary individuals.
Note: In December, the average maximum UV index of 4 translate into the following recommendations:
Take precautions. Light skin individuals may get burned in less than 30 minutes. The Sun's most intense and consequently most harmful UV radiation during midday hours should be decreased by minimizing exposure and seeking shade. A wide-brim hat offers excellent sun protection for eyes, ears, face, and neck. Sunglasses with UVA and UVB protection significantly reduce eye damage from sun exposure. Tightly woven, loose-fitting clothes provide additional protection from the Sun.
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FAQ

What is the coldest month in Fullerton?

The coldest month in Fullerton, California, is December, with an average high-temperature of 64°F (17.8°C) and an average low-temperature of 50.9°F (10.5°C).

What is the temperature in December in Fullerton?

In Fullerton, California, in December, the average high-temperature is 64°F (17.8°C), and the average low-temperature is 50.9°F (10.5°C).

What is the average humidity in December in Fullerton?

The average relative humidity in December in Fullerton is 55%.

How much does it rain in Fullerton in December?

In Fullerton, in December, during 6.6 rainfall days, 1.54" (39mm) of precipitation is typically accumulated.

What is the wettest month in Fullerton?

December is the month with the most rainfall in Fullerton. Rain falls for 6.6 days and accumulates 1.54" (39mm) of precipitation.

What is the month with the shortest days in Fullerton?

The month with the shortest days in Fullerton, California, is December, with an average of 9.9h of daylight.

How many hours of daylight does Fullerton have in December?

In Fullerton, the average length of the day in December is 9.9h.

What is the month with the least sunshine in Fullerton?

December has the least sunshine of the year in Fullerton, California, with an average of 6.7h of sunshine.

How many hours of sunshine does Fullerton have in December?

The average sunshine in December in Fullerton, California, is 6.7h.

When is the lowest UV index in Fullerton?

January, February, November and December, with an average maximum UV index of 4, are months with the lowest UV index in Fullerton.

What is the UV index intensity in December in Fullerton?

In Fullerton, California, the average daily maximum UV index in December is 4. A UV Index estimate of 3 to 5 represents a medium hazard to health from the exposure to the Sun's UV rays.

Average temperature in December
Fullerton, CA

Average temperature in December - Fullerton, CA
  • Average high temperature in December: 64°F

The warmest month (with the highest average high temperature) is August (83.5°F).
The month with the lowest average high temperature is December (64°F).

  • Average low temperature in December: 50.9°F

The month with the highest average low temperature is August (65.5°F).
The coldest month (with the lowest average low temperature) is February (50.2°F).

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Average pressure in December
Fullerton, CA

Average pressure in December - Fullerton, CA
  • Average pressure in December: 30.07"

The month with the highest atmospheric pressure is January (30.1").
The month with the lowest atmospheric pressure is June (29.88").

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Average wind speed in December
Fullerton, CA

Average wind speed in December - Fullerton, CA
  • Average wind speed in December: 5.1mph

The windiest month (with the highest average wind speed) is April (6mph).
The calmest months (with the lowest average wind speed) are September and October (4.7mph).

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Average humidity in December
Fullerton, CA

Average humidity in December - Fullerton, CA
  • Average humidity in December: 55%

The month with the highest relative humidity is June (65%).
The month with the lowest relative humidity is November (51%).

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Average rainfall in December
Fullerton, CA

Average rainfall in December - Fullerton, CA
  • Average rainfall in December: 1.54"

The wettest month (with the highest rainfall) is December (1.54").
The driest month (with the least rainfall) is June (0.04").

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Average rainfall days in December
Fullerton, CA

Average rainfall days in December - Fullerton, CA
  • Average rainfall days in December: 6.6 days

The month with the highest number of rainy days is March (7.3 days).
The month with the least rainy days is June (1.5 days).

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

Average daylight in December / Average sunshine in December - Fullerton, CA
  • Average daylight in December: 9.9h

The month with the longest days is June (Average daylight: 14.4h).
The month with the shortest days is December (Average daylight: 9.9h).

  • Average sunshine in December: 6.7h

Months with the most sunshine are July and August (Average sunshine: 12h).
The month with the least sunshine is December (Average sunshine: 6.7h).

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Average sunshine days in December
Fullerton, CA

Average sunshine days in December - Fullerton, CA
  • Average sunshine days in December: 23.2 days

The month with the most sunshine days is August (25.8 days).
The month with the least sunshine days is February (20.6 days).

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Average UV index in December
Fullerton, CA

Average UV index in December - Fullerton, CA
  • Average UV index in December: 4

Months with the highest UV index are June, July, August and September (UV index 6).
Months with the lowest UV index are January, February, November and December (UV index 4).

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Average cloud cover in December
Fullerton, CA

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

Months with the most cloud cover are March and December (Cloud cover 22).
The month with the least cloud cover is August (Cloud cover 5).

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Average visibility in December
Fullerton, CA

Average visibility in December - Fullerton, 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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