December weather forecast and climate
Westmont, CA

Weather in December

December, the first month of the winter, in Westmont, is still a comfortable month, with temperature in the range of an average high of 64°F (17.8°C) and an average low of 51.4°F (10.8°C).

Temperature

The coldest month is December, with an average high-temperature of 64°F (17.8°C) and an average low-temperature of 51.4°F (10.8°C).

Humidity

In Westmont, California, the average relative humidity is 56%.

Rainfall

In Westmont, during December, the rain falls for 5 days and regularly aggregates up to 1.3" (33mm) of precipitation. Throughout the year, there are 47.6 rainfall days, and 7.24" (184mm) of precipitation is accumulated.

Daylight

December has the shortest days of the year in Westmont, California, with an average of 9.9h of daylight.

Sunshine

The month with the least sunshine is December, with an average of 6.7h of sunshine.

UV index

January, February, November and December, with an average maximum UV index of 4, are months with the lowest UV index in Westmont. A UV Index reading of 3 to 5 represents a moderate health risk from the exposure to the Sun's UV rays for the average person.
Note: The average daily UV index of 4 transform into the following instructions:
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 Westmont?

December is the coldest month, with an average high-temperature of 64°F (17.8°C) and an average low-temperature of 51.4°F (10.8°C).

What is the temperature in December in Westmont?

The average high-temperature, in December, in Westmont, California, is 64°F (17.8°C), while the average low-temperature is 51.4°F (10.8°C).

What is the average humidity in December in Westmont?

In Westmont, California, the average relative humidity in December is 56%.

How much does it rain in Westmont in December?

In December, in Westmont, the rain falls for 5 days. Throughout December, 1.3" (33mm) of precipitation is accumulated.

What is the month with the shortest days in Westmont?

With an average of 9.9h of daylight, December has the shortest days of the year in Westmont, California.

What is the average length of the day in December in Westmont?

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

What is the month with the least sunshine in Westmont?

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

How long on average sun shines in December in Westmont?

The average sunshine in December in Westmont is 6.7h.

When is the lowest UV index in Westmont?

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

What is the UV index intensity in December in Westmont?

In December, the average daily maximum UV index in Westmont is 4. A UV Index value of 3 to 5 symbolizes a moderate vulnerability from the exposure to the Sun's UV rays.

Average temperature in December
Westmont, CA

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

The warmest month (with the highest average high temperature) is August (80.2°F).
The month with the lowest average high temperature is December (64°F).

  • Average low temperature in December: 51.4°F

The month with the highest average low temperature is August (64.9°F).
The coldest month (with the lowest average low temperature) is February (51.1°F).

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Average pressure in December
Westmont, CA

Average pressure in December - Westmont, 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 (29.89").

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Average wind speed in December
Westmont, CA

Average wind speed in December - Westmont, CA
  • Average wind speed in December: 5.5mph

The windiest month (with the highest average wind speed) is April (6.4mph).
The calmest month (with the lowest average wind speed) is September (4.9mph).

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Average humidity in December
Westmont, CA

Average humidity in December - Westmont, CA
  • Average humidity in December: 56%

The month with the highest relative humidity is June (70%).
The month with the lowest relative humidity is November (54%).

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Average rainfall in December
Westmont, CA

Average rainfall in December - Westmont, CA
  • Average rainfall in December: 1.3"

The wettest month (with the highest rainfall) is January (1.42").
The driest month (with the least rainfall) is June (0.08").

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Average rainfall days in December
Westmont, CA

Average rainfall days in December - Westmont, CA
  • Average rainfall days in December: 5 days

The month with the highest number of rainy days is March (6.5 days).
The month with the least rainy days is June (1.7 days).

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

Average daylight in December / Average sunshine in December - Westmont, 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: 11.9h).
The month with the least sunshine is December (Average sunshine: 6.7h).

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Average sunshine days in December
Westmont, CA

Average sunshine days in December - Westmont, CA
  • Average sunshine days in December: 24.8 days

The month with the most sunshine days is October (25.5 days).
The month with the least sunshine days is June (21.4 days).

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Average UV index in December
Westmont, CA

Average UV index in December - Westmont, 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
Westmont, CA

Average cloud cover in December - Westmont, 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 7).

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Average visibility in December
Westmont, CA

Average visibility in December - Westmont, 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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