December weather forecast
Alta Loma, CA

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Weather in December

December, the first month of the winter in Alta Loma, is also an enjoyable month, with temperature in the range of an average high of 61.3°F (16.3°C) and an average low of 45.3°F (7.4°C).

Temperature

December, recording an average high temperature of 61.3°F (16.3°C) and a low temperature of 45.3°F (7.4°C), is Alta Loma's coldest month.

Humidity

In Alta Loma, the average relative humidity in December is 51%.

Rainfall

In Alta Loma, in December, it is raining for 6.4 days, with typically 1.57" (40mm) of accumulated precipitation. In Alta Loma, during the entire year, the rain falls for 50.5 days and collects up to 7.56" (192mm) of precipitation.

Daylight

With an average of 9h and 54min of daylight, December has the shortest days of the year in Alta Loma.
On the first day of December in Alta Loma, sunrise is at 6:38 am and sunset at 4:40 pm. On the last day of the month, sunrise is at 6:55 am and sunset at 4:51 pm PST.

Sunshine

In December, the average sunshine is 7h.

UV index

December is the month with the lowest UV index in Alta Loma, with an average maximum UV index of 3. A UV Index of 3 to 5 symbolizes a medium vulnerability from exposure to the Sun's UV radiation for the ordinary person.
Note: In December, the average maximum UV index of 3 translates into the following recommendations:
Undertake precautions - Guarding against sun damage is counselled. Avoid the Sun's strongest UV rays by seeking shade and limiting exposure during midday. Equip yourself with UVA and UVB-filtering sunglasses on clear, sunny days.
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Frequently asked questions

What is the coldest time of year in Alta Loma?

Temperature records in Alta Loma, California, mark December as the coldest month, with highs averaging 61.3°F (16.3°C) and lows at 45.3°F (7.4°C).

What is the temperature in December in Alta Loma?

In Alta Loma, 61.3°F (16.3°C) is the average high-temperature and 45.3°F (7.4°C) is the average low-temperature during December. The average heat index (a.k.a. 'apparent temperature', 'feels like'), which calculates the temperature value influenced by the moisture in the air, in September is computed to be 89.6°F (32°C).

What is the average humidity in December in Alta Loma?

The average relative humidity in December in Alta Loma, California, is 51%.

How much does it rain in Alta Loma in December?

In Alta Loma, California, in December, during 6.4 rainfall days, 1.57" (40mm) of precipitation is typically accumulated.

What is the month with the shortest days in Alta Loma?

December has the shortest days of the year in Alta Loma, with an average of 9h and 54min of daylight.

What is the average length of the day in December in Alta Loma?

In Alta Loma, California, the average day length in December is 9h and 55min.

When is the sunrise / sunset in December in Alta Loma?

In December, on the first day of the month, sunrise is at 6:38 am and sunset at 4:40 pm. On the last day of the month, in Alta Loma, sunrise is at 6:55 am and sunset at 4:51 pm PST.

How many hours of sunshine does Alta Loma have in December?

The average sunshine duration in December in Alta Loma, California, is 7h.

When is the lowest UV index in Alta Loma?

The month with the lowest UV index is December, with an average maximum UV index of 3.

How high is the UV index in December in Alta Loma?

The average daily maximum UV index in December in Alta Loma is 3. A UV Index reading of 3 to 5 represents a moderate health threat from unsafe 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
Alta Loma, CA

Average temperature in December - Alta Loma, CA
  • Average high temperature in December: 61.3°F

The warmest month (with the highest average high temperature) is August (91.2°F).
The month with the lowest average high temperature is December (61.3°F).

  • Average low temperature in December: 45.3°F

The month with the highest average low temperature is August (66.7°F).
The coldest month (with the lowest average low temperature) is February (45.1°F).

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Average pressure in December
Alta Loma, CA

Average pressure in December - Alta Loma, CA
  • Average pressure in December: 30.07"Hg

The month with the highest atmospheric pressure is January (30.1"Hg).
The month with the lowest atmospheric pressure is June (29.86"Hg).

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Average wind speed in December
Alta Loma, CA

Average wind speed in December - Alta Loma, CA
  • Average wind speed in December: 5.2mph

The windiest months (with the highest average wind speed) are April and May (5.9mph).
The calmest month (with the lowest average wind speed) is September (4.5mph).

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Average humidity in December
Alta Loma, CA

Average humidity in December - Alta Loma, CA
  • Average humidity in December: 51%

The months with the highest relative humidity are February, March and May (53%).
The month with the lowest relative humidity is August (41%).

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Average rainfall in December
Alta Loma, CA

Average rainfall in December - Alta Loma, CA
  • Average rainfall in December: 1.57"

The wettest month (with the highest rainfall) is February (1.73").
The driest month (with the least rainfall) is June (0.04").

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Average rainfall days in December
Alta Loma, CA

Average rainfall days in December - Alta Loma, CA
  • Average rainfall days in December: 6.4 days

The month with the highest number of rainy days is March (7.5 days).
The month with the least rainy days is June (1.2 days).

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Average daylight in December /
Average sunshine in December
Alta Loma, CA

Average daylight in December / Average sunshine in December - Alta Loma, 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: 7h and 0min

The month with the most sunshine is July (Average sunshine: 12h and 6min).
The month with the least sunshine is February (Average sunshine: 6h and 54min).

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Average sunshine days in December
Alta Loma, CA

Average sunshine days in December - Alta Loma, CA
  • Average sunshine days in December: 23.2 days

The month with the most sunshine days is June (27.7 days).
The month with the least sunshine days is February (21.4 days).

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Average UV index in December
Alta Loma, CA

Average UV index in December - Alta Loma, CA
  • Average UV index in December: 3

The months with the highest UV index are July and August (UV index 7).
The month with the lowest UV index is December (UV index 3).

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Average cloud cover in December
Alta Loma, CA

Average cloud cover in December - Alta Loma, CA
  • Average cloud cover in December: 21

The months with the most cloud cover are March and December (Cloud cover 21).
The month with the least cloud cover is August (Cloud cover 4).

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Average visibility in December
Alta Loma, CA

Average visibility in December - Alta Loma, 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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Alta Loma, California, USA

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