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December Weather in San Sebastian, Puerto Rico

Last updated: August 31, 2025

In San Sebastian, Puerto Rico, the average temperature in December hovers around 25°C (77°F), with a minimum of 21°C (69°F) and a maximum reaching 31°C (87°F). Expect 28 mm (1.1 in) of precipitation spread over 9 days, contributing to an average humidity of 76%. Perfect for those who enjoy a warm, slightly damp climate!

December Temperature in San Sebastian

In December, in San Sebastian, the average temperature is 25°C (77°F). Maximums can reach 31°C (87°F) and minimums can be as low as 21°C (69°F). This pleasant climate makes San Sebastian an ideal destination for travelers seeking comfortable temperatures and enjoyable outdoor activities.

December Weather in San Sebastian: Daily Temperature Highs, Lows, and Averages

The chart illustrates December temperature patterns in San Sebastian, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In San Sebastian, December typically has an average temperature of 25°C (77°F), with highs reaching up to 31°C (87°F) and lows dropping to around 21°C (69°F).
JanFebMarAprMayJunJulAugSepOctNovDec767675777880818180797877
Data source: Temperature data for San Sebastian generated using information from the Copernicus Climate Change Service.
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The average of daily temperatures (24 hours) calculated across all days in the month.

December Precipitation in San Sebastian

In San Sebastian in December, the precipitation amount is 28 mm (1.1 in) spread over 9 days.

December Precipitation Trends in San Sebastian

The chart displays monthly precipitation patterns in San Sebastian, with values for each month alongside December’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how December’s conditions compare to those of other months. In San Sebastian, December typically receives around 28 mm (1.1 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec2233687295851031061921229828
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
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December Humidity in San Sebastian

In San Sebastian in December, humidity is 76%. With an average temperature of 25°C (77°F), this humidity feels like a warm, heavy blanket wrapping around you, making traveling feel muggy and requiring frequent breaks to stay refreshed.

December Average Humidity in San Sebastian

This chart illustrates the average monthly humidity levels in San Sebastian, with December’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In December, average humidity in San Sebastian is approximately 76%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec76%75%74%75%75%77%80%80%79%78%78%76%
Data source: Humidity data for December generated using information from the Copernicus Climate Change Service.

December UV Index in San Sebastian

In San Sebastian in December, the maximum UV index is 8, which corresponds to a very high Exposure Category. This means that the time to burn is only 15 minutes. For more detailed information, you can refer to the Hourly UV Index in San Sebastian.

Maximum UV Index Levels in San Sebastian for December

The chart shows the monthly maximum UV Index (UVI) for San Sebastian in December, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues. In December, the maximum UV index in San Sebastian typically reaches 8, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec911131314131313131298
Data source: San Sebastian December UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

  •  Extreme (11+): Avoid the sun, stay in shade.
  •  Very High (8-10): Limit sun exposure.
  •  High (6-7): Use SPF 30+ and protective clothing.
  •  Moderate (3-5): Midday shade recommended.
  •  Low (0-2): No protection needed.

How December Weather in San Sebastian Compares to Other Months

Weather in San Sebastian varies notably across the year, with each month offering distinct climate conditions. This page compares December’s weather to other months in San Sebastian, focusing on differences in temperature, rainfall, humidity, and UV levels.

This table compares monthly weather conditions in San Sebastian, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather24°C (76°F)22 mm (0.9 inches)76%very high
February Weather24°C (76°F)33 mm (1.3 inches)75%extreme
March Weather24°C (76°F)68 mm (2.7 inches)74%extreme
April Weather25°C (77°F)72 mm (2.8 inches)75%extreme
May Weather26°C (79°F)95 mm (3.7 inches)75%extreme
June Weather27°C (80°F)85 mm (3.4 inches)77%extreme
July Weather27°C (81°F)103 mm (4.1 inches)80%extreme
August Weather27°C (81°F)106 mm (4.2 inches)80%extreme
September Weather27°C (80°F)192 mm (7.6 inches)79%extreme
October Weather26°C (79°F)122 mm (4.8 inches)78%extreme
November Weather26°C (78°F)98 mm (3.9 inches)78%very high
December Weather25°C (77°F)28 mm (1.1 inches)76%very high

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