December weather forecast
San Marcos, El Salvador

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Weather in December

Arriving at the final month of the year, December embraces the cooler and drier season with an average low temperature of 19.1°C (66.4°F). December records the lowest rainfall of the year at 6mm (0.24") over nearly three days, indicating the complete shift to the dry season. More sunlight is present with the skies clearing up from the previously high cloud cover experienced in the wet season. Despite that, average daylight hours tend to be shorter, amounting to about 11.3 hours. The soothing effect of the cooler breeze, with wind gusts reaching 11.4 KPH, complements the overall weather, making San Marcos particularly inviting during this time.

Temperature

December's onset brings an average high-temperature of a still tropical 30.8°C (87.4°F), showing a minute difference from November's 30.3°C (86.5°F). San Marcos's nighttime temperature in December drops to an average of 19.1°C (66.4°F).

Heat index

Throughout December, the heat index is appraised at a fiery hot 37°C (98.6°F). Undertake special precautions, the probability of heat exhaustion and heat cramps is high. Prolonged activity may provoke heatstroke.
Note that heat index values are valued for light wind and location in the shade. The direct sunshine could escalate the heat index values by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'apparent temperature' or 'real feel', gives a temperature feeling by integrating air temperature and humidity. Elements such as metabolic variations, pregnancy, and physical exertion can influence one's weather perception. When exposed to direct sunlight, it's possible for the heat index to increase by as much as 15 Fahrenheit (8 Celsius) degrees. Heat index values hold particular significance for children. Younglings are generally more in peril than adults due to their reduced perspiration. Coupled with a larger skin surface relative to their tiny bodies and greater heat production because of their activity, they become more at risk.
One of the main methods the human body employs to cool down is by perspiring, as this process allows sweat to evaporate and remove excess heat. An increase in relative humidity retards evaporation, subsequently reducing the body's heat removal rate and leading to a sensation of being overly warm. When body temperature rises due to excess heat gain beyond its removal capability, one might experience heat-related disorders.

Humidity

In San Marcos, the average relative humidity in December is 69%.

Rainfall

In San Marcos, in December, during 2.8 rainfall days, 6mm (0.24") of precipitation is typically accumulated. In San Marcos, during the entire year, the rain falls for 196.7 days and collects up to 1216mm (47.87") of precipitation.

Daylight

December has the shortest days of the year, with an average of 11h and 18min of daylight.
On the first day of the month, sunrise is at 06:04 and sunset at 17:27. On the last day of December, sunrise is at 06:19 and sunset at 17:40 CST.

Sunshine

The months with the least sunshine are January and December, with an average of 7.7h of sunshine.

UV index

The months with the lowest UV index are May through December, with an average maximum UV index of 6. A UV Index reading of 6 to 7 represents a high health vulnerability from unprotected exposure to Sun's UV rays for average individuals.
Note: A maximum UV index of 6 in December translates into the following recommendations:
Undertake protective measures and comply with sun safety rules. Shielding against skin and eye damage is essential. Stay in the shade and limit direct Sun exposure from 10 a.m. to 4 p.m., a time when UV radiation is particularly strong. Remember, however, that shade structures may not provide complete protection. In the presence of strong sunlight, it's crucial to wear sunglasses that ward off UVA and UVB rays.

Frequently asked questions

Is it hot during December?

In San Marcos, in December, the average high-temperature is 30.8°C (87.4°F), and the average low-temperature is 19.1°C (66.4°F). In December, the average heat index (a.k.a. 'real feel', 'felt air temperature'), which represents the influence of relative humidity on air temperature, is appraised at 37°C (98.6°F).

What is the average humidity in December?

In San Marcos, the average relative humidity in December is 69%.

How many days does it rain in December?

In San Marcos, during December, the rain falls for 2.8 days and regularly aggregates up to 6mm (0.24") of precipitation.

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

December has the shortest days of the year, with an average of 11h and 18min of daylight.

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

The average day length in December is 11h and 20min.

What time are sunrise and sunset in December in San Marcos?

On the first day of December, sunrise is at 06:04 and sunset at 17:27. On the last day of the month, sunrise is at 06:19 and sunset at 17:40 CST.

What are the months with the least sunshine?

January and December, with an average of 7.7h of sunshine, are months with the least sunshine.

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

The average sunshine duration in December is 7.7h.

What are the months with the lowest UV index?

The months with the lowest UV index are May through December, with an average maximum UV index of 6.

What is the UV index reading in December?

The average daily maximum UV index in December is 6. A UV Index estimate of 6 to 7 represents a high 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 temperature in December
San Marcos, El Salvador

Average temperature in December - San Marcos, El Salvador
  • Average high temperature in December: 30.8°C

The warmest months (with the highest average high temperature) are March and April (33.4°C).
The month with the lowest average high temperature is October (29.7°C).

  • Average low temperature in December: 19.1°C

The month with the highest average low temperature is May (22.6°C).
The coldest month (with the lowest average low temperature) is January (19°C).

Average pressure in December
San Marcos, El Salvador

Average pressure in December - San Marcos, El Salvador
  • Average pressure in December: 1013mbar

The month with the highest atmospheric pressure is January (1013.6mbar).
The months with the lowest atmospheric pressure are May and October (1011.3mbar).

Average wind speed in December
San Marcos, El Salvador

Average wind speed in December - San Marcos, El Salvador
  • Average wind speed in December: 7.3km/h

The windiest month (with the highest average wind speed) is January (8km/h).
The calmest month (with the lowest average wind speed) is June (4.4km/h).

Average humidity in December
San Marcos, El Salvador

Average humidity in December - San Marcos, El Salvador
  • Average humidity in December: 69%

The months with the highest relative humidity are September and October (82%).
The month with the lowest relative humidity is March (61%).

Average rainfall in December
San Marcos, El Salvador

Average rainfall in December - San Marcos, El Salvador
  • Average rainfall in December: 6mm

The wettest month (with the highest rainfall) is May (267mm).
The driest month (with the least rainfall) is January (2mm).

Average rainfall days in December
San Marcos, El Salvador

Average rainfall days in December - San Marcos, El Salvador
  • Average rainfall days in December: 2.8 days

The month with the highest number of rainy days is May (26.9 days).
The month with the least rainy days is January (2.3 days).

Average daylight in December /
Average sunshine in December
San Marcos, El Salvador

Average daylight in December / Average sunshine in December - San Marcos, El Salvador
  • Average daylight in December: 11h and 2min

The month with the longest days is June (Average daylight: 12h and 54min).
The month with the shortest days is December (Average daylight: 11h and 18min).

  • Average sunshine in December: 7h and 4min

The month with the most sunshine is April (Average sunshine: 11h and 18min).
The months with the least sunshine are January and December (Average sunshine: 7h and 42min).

Average sunshine days in December
San Marcos, El Salvador

Average sunshine days in December - San Marcos, El Salvador
  • Average sunshine days in December: 27.1 days

The month with the most sunshine days is January (27.7 days).
The month with the least sunshine days is September (2.5 days).

Average UV index in December
San Marcos, El Salvador

Average UV index in December - San Marcos, El Salvador
  • Average UV index in December: 6

The months with the highest UV index are January, February, March and April (UV index 7).
The months with the lowest UV index are May, June, July, August, September, October, November and December (UV index 6).

Average cloud cover in December
San Marcos, El Salvador

Average cloud cover in December - San Marcos, El Salvador
  • Average cloud cover in December: 14

The month with the most cloud cover is September (Cloud cover 41).
The month with the least cloud cover is January (Cloud cover 13).

Average visibility in December
San Marcos, El Salvador

Average visibility in December - San Marcos, El Salvador
  • Average visibility in December: 10km

The months with the highest visibility are January, February, March, April and December (10km).
The months with the lowest visibility are June, August, September and October (8km).

San Marcos, El Salvador

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