December weather forecast
San Marcos, TX

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Weather in December

December, the first month of the winter in San Marcos, is still a mild month, with an average temperature ranging between max 60.4°F (15.8°C) and min 45.5°F (7.5°C).

Temperature

The advent of December brings a subtle shift in temperature, with the average high moving from a pleasant 68.2°F (20.1°C) in November to a mild 60.4°F (15.8°C). The nighttime temperature, during December, averages of 45.5°F (7.5°C).

Humidity

In December, the average relative humidity in San Marcos, Texas, is 72%.

Rainfall

In December, the rain falls for 11.7 days. Throughout December, 1.57" (40mm) of precipitation is accumulated. In San Marcos, during the entire year, the rain falls for 151.8 days and collects up to 26.89" (683mm) of precipitation.

Snowfall

January, February and December are months with snowfall. December is the first month it typically snows. Throughout December, in the average 0.1 snowfall days, it receives 0.04" (1mm) of snow. Throughout the year, there are 0.7 snowfall days, and 0.28" (7mm) of snow is accumulated.

Daylight

The month with the shortest days is December, with an average of 10h and 18min of daylight.
On the first day of the month, sunrise is at 7:10 am and sunset at 5:31 pm. On the last day of December, sunrise is at 7:27 am and sunset at 5:43 pm CST.

Sunshine

The month with the least sunshine is December, with an average of 5.2h of sunshine.

UV index

The month with the lowest UV index is December, with an average maximum UV index of 3. A UV Index of 3 to 5 symbolizes a medium health hazard from unprotected exposure to Sun's UV rays for the ordinary person.
Note: A daily maximum UV index of 3 in December translates into the following instructions:
Undertake precautions - It is suggested to shield oneself from sunburn. To prevent harmful UV exposure, minimize direct contact with the Sun around midday. A hat with a generous brim can prevent nearly 50% of UV rays from reaching your eyes. Be aware! The reflective nature of snow can magnify the Sun's UV radiation almost twofold.

Frequently asked questions

What is the temperature in December?

In December, in San Marcos, the average high-temperature is 60.4°F (15.8°C), and the average low-temperature is 45.5°F (7.5°C). The average heat index (a.k.a. 'real feel', 'apparent temperature'), which combines air temperature and relative humidity, in September is appraised at 100.4°F (38°C).

What is the average humidity in December?

In December, the average relative humidity is 72%.

How much does it rain in December?

In San Marcos, in December, during 11.7 rainfall days, 1.57" (40mm) of precipitation is typically accumulated.

When does it start to snow in San Marcos?

December is the first month it typically snows. Throughout December, in the average 0.1 snowfall days, it receives 0.04" (1mm) of snow.

What is the month with the shortest days?

The month with the shortest days is December, with an average of 10h and 18min of daylight.

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

In December, the average day length is 10h and 16min.

What time are sunrise and sunset in December?

In December, on the first day of the month, sunrise is at 7:10 am and sunset at 5:31 pm. On the last day of the month, sunrise is at 7:27 am and sunset at 5:43 pm CST.

What is the month with the least sunshine?

The month with the least sunshine is December, with an average of 5.2h of sunshine.

How long on average sun shines in December?

In San Marcos, the average sunshine duration in December is 5.2h.

When is the lowest UV index?

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?

The average daily maximum UV index in December is 3. A UV Index estimate of 3 to 5 represents a moderate vulnerability from exposure to the Sun's UV radiation.
Average humidity
Average rainfall days
Average snowfall
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in December
San Marcos, TX

Average temperature in December - San Marcos, TX
  • Average high temperature in December: 60.4°F

The warmest month (with the highest average high temperature) is August (95.9°F).
The month with the lowest average high temperature is January (59.9°F).

  • Average low temperature in December: 45.5°F

The month with the highest average low temperature is August (74.7°F).
The coldest month (with the lowest average low temperature) is January (42.8°F).

Average pressure in December
San Marcos, TX

Average pressure in December - San Marcos, TX
  • Average pressure in December: 30.11"Hg

The month with the highest atmospheric pressure is January (30.15"Hg).
The month with the lowest atmospheric pressure is June (29.9"Hg).

Average wind speed in December
San Marcos, TX

Average wind speed in December - San Marcos, TX
  • Average wind speed in December: 8.1mph

The windiest month (with the highest average wind speed) is February (9.1mph).
The calmest month (with the lowest average wind speed) is September (6.1mph).

Average humidity in December
San Marcos, TX

Average humidity in December - San Marcos, TX
  • Average humidity in December: 72%

The month with the highest relative humidity is May (77%).
The month with the lowest relative humidity is August (62%).

Average rainfall in December
San Marcos, TX

Average rainfall in December - San Marcos, TX
  • Average rainfall in December: 1.57"

The wettest month (with the highest rainfall) is May (4.57").
The driest month (with the least rainfall) is February (1.1").

Average rainfall days in December
San Marcos, TX

Average rainfall days in December - San Marcos, TX
  • Average rainfall days in December: 11.7 days

The month with the highest number of rainy days is May (16.6 days).
The month with the least rainy days is January (9.4 days).

Average snowfall in December
San Marcos, TX

Average snowfall in December - San Marcos, TX
  • Average snowfall in December: 0.04"

The months with the highest snowfall are January and February (0.12").
The months with the least snowfall are March, April, May, June, July, August, September, October and November (0").

Average snowfall days in December
San Marcos, TX

Average snowfall days in December - San Marcos, TX
  • Average snowfall days in December: 0.1 days

The months with the highest number of snowfall days are January and February (0.3 days).
The months with the least snowfall days are March, April, May, June, July, August, September, October and November (0 days).

Average daylight in December /
Average sunshine in December
San Marcos, TX

Average daylight in December / Average sunshine in December - San Marcos, TX
  • Average daylight in December: 10h and 2min

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

  • Average sunshine in December: 5h and 1min

The months with the most sunshine are July and August (Average sunshine: 10h and 0min).
The month with the least sunshine is December (Average sunshine: 5h and 12min).

Average sunshine days in December
San Marcos, TX

Average sunshine days in December - San Marcos, TX
  • Average sunshine days in December: 17.1 days

The month with the most sunshine days is January (19.4 days).
The month with the least sunshine days is May (11.9 days).

Average UV index in December
San Marcos, TX

Average UV index in December - San Marcos, TX
  • Average UV index in December: 3

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

Average cloud cover in December
San Marcos, TX

Average cloud cover in December - San Marcos, TX
  • Average cloud cover in December: 43

The month with the most cloud cover is March (Cloud cover 49).
The month with the least cloud cover is August (Cloud cover 25).

Average visibility in December
San Marcos, TX

Average visibility in December - San Marcos, TX
  • Average visibility in December: 6mi

The months with the highest visibility are January, February, March, April, June, July, August, September, October, November and December (6mi).
The month with the lowest visibility is May (5mi).

San Marcos, Texas, USA

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