December weather forecast
Lake San Marcos, CA

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Weather in December

The first month of the winter, December, is still a comfortable month in Lake San Marcos, California, with an average temperature varying between 63.3°F (17.4°C) and 48.2°F (9°C).

Temperature

Lake San Marcos's coldest season falls during February and December, averaging a high-temperature of 63.3°F (17.4°C).

Humidity

In December, the average relative humidity is 60%.

Rainfall

The month with the most rainfall in Lake San Marcos is December, when the rain falls for 5.9 days and typically aggregates up to 1.22" (31mm) of precipitation.

Daylight

December has the shortest days of the year in Lake San Marcos, with an average of 10h and 0min of daylight.
On the first day of December, sunrise is at 6:34 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

December has the least sunshine of the year, with an average of 6.8h of sunshine.

UV index

The months with the lowest UV index in Lake San Marcos are January through March, November and December, with an average maximum UV index of 4. A UV Index estimate of 3 to 5 represents a moderate threat to health from exposure to the Sun's UV rays for the ordinary person.
Note: The maximum UV index of 4 during December leads to these instructions:
Heed the precautions - Suggestions to avoid sunburn are made. When the Sun's UV radiation is most intense during midday, it's best to find shade and limit exposure. A hat with a broad brim is indispensable, filtering out up to half of UV rays.
Updated: Feb 10, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What are the coldest months in Lake San Marcos?

Lake San Marcos experiences the lowest of its temperatures in February and December, when the average high-temperatures rise to 63.3°F (17.4°C).

What is the usual temperature for Lake San Marcos in December?

In December, the average high-temperature and low-temperature in Lake San Marcos, California, are 63.3°F (17.4°C) and 48.2°F (9°C) respectively. In September, the average heat index (a.k.a. 'felt air temperature', 'real feel'), which factors the actual air temperature with the relative humidity, is calculated to be 82.4°F (28°C).

What is the average humidity in December in Lake San Marcos?

The average relative humidity in December in Lake San Marcos, California, is 60%.

What is the rainiest month in Lake San Marcos?

The month with the most rainfall in Lake San Marcos is December, when the rain falls for 5.9 days and typically aggregates up to 1.22" (31mm) of precipitation.

How many days does it rain in December in Lake San Marcos?

In Lake San Marcos, in December, it is raining for 5.9 days, with typically 1.22" (31mm) of accumulated precipitation.

What is the month with the shortest days in Lake San Marcos?

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

How many hours of daylight does Lake San Marcos have in December?

In Lake San Marcos, California, the average day length in December is 10h and 1min.

When are sunrise and sunset in December in Lake San Marcos?

In December, on the first day of the month, sunrise is at 6:34 am and sunset at 4:41 pm. On the last day of the month, in Lake San Marcos, sunrise is at 6:51 am and sunset at 4:52 pm PST.

What is the month with the least sunshine in Lake San Marcos?

With an average of 6.8h of sunshine, December has the least sunshine of the year in Lake San Marcos.

How long on average sun shines in December in Lake San Marcos?

In Lake San Marcos, California, the average sunshine duration in December is 6.8h.

What is the month with the lowest UV index in Lake San Marcos?

The months with the lowest UV index are January through March, November and December, with an average maximum UV index of 4.

How high is the UV index in December in Lake San Marcos?

In December, the average daily maximum UV index in Lake San Marcos is 4. A UV Index reading of 3 to 5 represents a moderate health threat from unprotected exposure to UV radiation.
Average humidity
Average rainfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in December
Lake San Marcos, CA

Average temperature in December - Lake San Marcos, CA
  • Average high temperature in December: 63.3°F

The warmest month (with the highest average high temperature) is August (81.9°F).
The months with the lowest average high temperature are February and December (63.3°F).

  • Average low temperature in December: 48.2°F

The month with the highest average low temperature is August (64.2°F).
The coldest month (with the lowest average low temperature) is February (48°F).

Average pressure in December
Lake San Marcos, CA

Average pressure in December - Lake San Marcos, CA
  • Average pressure in December: 30.06"Hg

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

Average wind speed in December
Lake San Marcos, CA

Average wind speed in December - Lake San Marcos, CA
  • Average wind speed in December: 5mph

The windiest month (with the highest average wind speed) is April (5.7mph).
The calmest month (with the lowest average wind speed) is October (4.4mph).

Average humidity in December
Lake San Marcos, CA

Average humidity in December - Lake San Marcos, CA
  • Average humidity in December: 60%

The month with the highest relative humidity is May (70%).
The month with the lowest relative humidity is November (56%).

Average rainfall in December
Lake San Marcos, CA

Average rainfall in December - Lake San Marcos, CA
  • Average rainfall in December: 1.22"

The wettest month (with the highest rainfall) is December (1.22").
The driest month (with the least rainfall) is June (0.08").

Average rainfall days in December
Lake San Marcos, CA

Average rainfall days in December - Lake San Marcos, CA
  • Average rainfall days in December: 5.9 days

The month with the highest number of rainy days is March (7.8 days).
The month with the least rainy days is June (1.2 days).

Average daylight in December /
Average sunshine in December
Lake San Marcos, CA

Average daylight in December / Average sunshine in December - Lake San Marcos, 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 5min

The month with the most sunshine is July (Average sunshine: 12h and 6min).
The month with the least sunshine is December (Average sunshine: 6h and 48min).

Average sunshine days in December
Lake San Marcos, CA

Average sunshine days in December - Lake San Marcos, CA
  • Average sunshine days in December: 22.5 days

The month with the most sunshine days is August (25.8 days).
The month with the least sunshine days is February (20 days).

Average UV index in December
Lake San Marcos, CA

Average UV index in December - Lake San Marcos, 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, March, November and December (UV index 4).

Average cloud cover in December
Lake San Marcos, CA

Average cloud cover in December - Lake San Marcos, CA
  • Average cloud cover in December: 23

The months with the most cloud cover are March and December (Cloud cover 23).
The month with the least cloud cover is August (Cloud cover 7).

Average visibility in December
Lake San Marcos, CA

Average visibility in December - Lake San Marcos, 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).

Lake San Marcos, California, USA

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