December weather forecast
Rancho Bernardo, CA

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Weather in December

The first month of the winter, December, is still a refreshing month in Rancho Bernardo, California, with an average temperature ranging between max 63.9°F (17.7°C) and min 47.7°F (8.7°C).

Temperature

With average high temperatures of 63.9°F (17.7°C) and lows of 47.7°F (8.7°C), December is the coldest month.

Humidity

In December, the average relative humidity is 59%.

Rainfall

In Rancho Bernardo, during December, the rain falls for 6.1 days and regularly aggregates up to 1.46" (37mm) of precipitation. In Rancho Bernardo, during the entire year, the rain falls for 54.7 days and collects up to 8.15" (207mm) of precipitation.

Daylight

With an average of 10h and 0min of daylight, December has the shortest days of the year.
On the first day of December, sunrise is at 6:33 am and sunset at 4:41 pm. On the last day of the month, sunrise is at 6:51 am and sunset at 4:52 pm PST.

Sunshine

The months with the least sunshine are January and 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. A UV Index of 3 to 5 symbolizes a moderate threat to health from exposure to the Sun's UV radiation for the ordinary person.
Note: In December, the maximum UV index of 4 suggests these recommendations:
Take precautions - Protection against sunburn is recommended. Avoid the Sun's strongest UV rays by seeking shade and limiting exposure during midday. On days when the sun blazes, arm yourself with sunglasses that block UVA and UVB radiation.
Updated: Jul 20, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What month is the coldest?

Temperature readings reach their annual highs in December, averaging 63.9°F (17.7°C) and a minimum average of 47.7°F (8.7°C).

What is the temperature in December?

December temperatures vary between a high-temperature of 63.9°F (17.7°C) and a low-temperature of 47.7°F (8.7°C). The average heat index (a.k.a. 'apparent temperature', 'feels like'), which takes the relative humidity and factors it into the air temperature reading, in September is appraised at 86°F (30°C).

What is the average humidity in December?

The average relative humidity in December is 59%.

How many days does it rain in December?

In Rancho Bernardo, in December, during 6.1 rainfall days, 1.46" (37mm) of precipitation is typically accumulated.

What is the month with the shortest days?

The month with the shortest days is December, with an average of 10h and 0min of daylight.

How many hours of daylight does Rancho Bernardo have in December?

In December, the average day length is 10h and 1min.

When are sunrise and sunset in December?

On the first day of December, sunrise is at 6:33 am and sunset at 4:41 pm. On the last day of the month, sunrise is at 6:51 am and sunset at 4:52 pm PST.

What is the month with the least sunshine?

The months with the least sunshine are January and December, with an average of 6.7h of sunshine.

How long on average sun shines in December?

In Rancho Bernardo, the average sunshine duration in December is 6.7h.

When is the lowest UV index?

The 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 Rancho Bernardo?

In Rancho Bernardo, the average daily maximum UV index in December is 4. A UV Index of 3 to 5 symbolizes 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
Rancho Bernardo, CA

Average temperature in December - Rancho Bernardo, CA
  • Average high temperature in December: 63.9°F

The warmest month (with the highest average high temperature) is August (84.2°F).
The month with the lowest average high temperature is December (63.9°F).

  • Average low temperature in December: 47.7°F

The month with the highest average low temperature is August (64.4°F).
The coldest month (with the lowest average low temperature) is February (47.1°F).

Average pressure in December
Rancho Bernardo, CA

Average pressure in December - Rancho Bernardo, CA
  • Average pressure in December: 30.06"Hg

The month with the highest atmospheric pressure is January (30.09"Hg).
The months with the lowest atmospheric pressure are June and September (29.87"Hg).

Average wind speed in December
Rancho Bernardo, CA

Average wind speed in December - Rancho Bernardo, CA
  • Average wind speed in December: 5mph

The windiest month (with the highest average wind speed) is April (5.5mph).
The calmest months (with the lowest average wind speed) are September and October (4.3mph).

Average humidity in December
Rancho Bernardo, CA

Average humidity in December - Rancho Bernardo, CA
  • Average humidity in December: 59%

The month with the highest relative humidity is May (68%).
The month with the lowest relative humidity is November (54%).

Average rainfall in December
Rancho Bernardo, CA

Average rainfall in December - Rancho Bernardo, CA
  • Average rainfall in December: 1.46"

The wettest month (with the highest rainfall) is February (1.61").
The driest month (with the least rainfall) is June (0.08").

Average rainfall days in December
Rancho Bernardo, CA

Average rainfall days in December - Rancho Bernardo, CA
  • Average rainfall days in December: 6.1 days

The month with the highest number of rainy days is March (7.2 days).
The month with the least rainy days is June (1.6 days).

Average daylight in December /
Average sunshine in December
Rancho Bernardo, CA

Average daylight in December / Average sunshine in December - Rancho Bernardo, CA
  • Average daylight in December: 10h and 0min

The month with the longest days is June (Average daylight: 14h and 18min).
The month with the shortest days is December (Average daylight: 10h and 0min).

  • Average sunshine in December: 6h and 4min

The month with the most sunshine is July (Average sunshine: 12h and 0min).
The months with the least sunshine are January and December (Average sunshine: 6h and 42min).

Average sunshine days in December
Rancho Bernardo, CA

Average sunshine days in December - Rancho Bernardo, CA
  • Average sunshine days in December: 23.5 days

The month with the most sunshine days is June (27 days).
The month with the least sunshine days is February (21.2 days).

Average UV index in December
Rancho Bernardo, CA

Average UV index in December - Rancho Bernardo, CA
  • Average UV index in December: 4

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

Average cloud cover in December
Rancho Bernardo, CA

Average cloud cover in December - Rancho Bernardo, CA
  • Average cloud cover in December: 23

The month with the most cloud cover is March (Cloud cover 24).
The month with the least cloud cover is August (Cloud cover 7).

Average visibility in December
Rancho Bernardo, CA

Average visibility in December - Rancho Bernardo, 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).

Rancho Bernardo, California, USA

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