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May Weather in San Marcos, Costa Rica

Last updated: August 23, 2025

In May, the average temperature in San Marcos, Costa Rica is a pleasant 18°C (65°F), with minimums dipping to 14°C (57°F) and highs reaching up to 26°C (79°F). The region experiences considerable moisture, with 532 mm (21.0 in) of precipitation spread over 29 days. Additionally, the average humidity sits comfortably at 69%, making the atmosphere feel refreshingly vibrant.

May Temperature in San Marcos

In May in San Marcos, the average temperature is 18°C (65°F). Maximum temperatures can reach 26°C (79°F), while minimums can drop to as low as 14°C (57°F). This mild climate makes San Marcos an ideal destination for travelers seeking comfortable weather.

May Weather in San Marcos: Daily Temperature Highs, Lows, and Averages

The chart illustrates May temperature patterns in San Marcos, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In San Marcos, May typically has an average temperature of 18°C (65°F), with highs reaching up to 26°C (79°F) and lows dropping to around 14°C (57°F).
JanFebMarAprMayJunJulAugSepOctNovDec636464656565656564646463
Data source: Temperature data for San Marcos 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.

May Precipitation in San Marcos

In San Marcos in May, the total precipitation amount is 532 mm (21.0 in), accumulated over a period of 29 days.

May Precipitation Trends in San Marcos

The chart displays monthly precipitation patterns in San Marcos, with values for each month alongside May’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how May’s conditions compare to those of other months. In San Marcos, May typically receives around 532 mm (21.0 inches) of precipitation spread over approximately 29 days.
JanFebMarAprMayJunJulAugSepOctNovDec35192815553239931540350860127278
Data source: Precipitation data for May generated using information from the Copernicus Climate Change Service.
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May Humidity in San Marcos

In San Marcos in May humidity is 69%. With an average temperature of 18°C (65°F), this humidity feels like a warm, damp blanket around you, making travel less comfortable and causing you to feel sticky and fatigued more quickly.

May Average Humidity in San Marcos

This chart illustrates the average monthly humidity levels in San Marcos, with May’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In May, average humidity in San Marcos is approximately 69%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec68%68%66%67%69%84%85%82%81%80%80%73%
Data source: Humidity data for May generated using information from the Copernicus Climate Change Service.

May UV Index in San Marcos

In San Marcos in May, the maximum UV index reaches an alarming 15, which falls into the extreme Exposure Category. With a time to burn of just 10 minutes, it's crucial to take precautions. For detailed information, you can check the Hourly UV Index in San Marcos.

Maximum UV Index Levels in San Marcos for May

The chart shows the monthly maximum UV Index (UVI) for San Marcos in May, 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 May, the maximum UV index in San Marcos typically reaches 15, which falls under the extreme exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec121415161514151414141211
Data source: San Marcos May 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 May Weather in San Marcos Compares to Other Months

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

This table compares monthly weather conditions in San Marcos, showing how May’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather17°C (63°F)35 mm (1.4 inches)68%extreme
February Weather18°C (64°F)19 mm (0.8 inches)68%extreme
March Weather18°C (65°F)28 mm (1.1 inches)66%extreme
April Weather18°C (65°F)155 mm (6.1 inches)67%extreme
May Weather18°C (65°F)532 mm (21.0 inches)69%extreme
June Weather18°C (66°F)399 mm (15.7 inches)84%extreme
July Weather18°C (65°F)315 mm (12.4 inches)85%extreme
August Weather18°C (65°F)403 mm (15.9 inches)82%extreme
September Weather18°C (65°F)508 mm (20.0 inches)81%extreme
October Weather18°C (64°F)601 mm (23.7 inches)80%extreme
November Weather18°C (64°F)272 mm (10.7 inches)80%extreme
December Weather17°C (64°F)78 mm (3.1 inches)72%extreme

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