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September Weather in San Sebastian, Guatemala

Last updated: August 23, 2025

In September, the average temperature in San Sebastian, Guatemala is a warm 26°C (80°F), making it a great time for outdoor activities. Temperatures can dip as low as 21°C (71°F) and soar to a maximum of 34°C (93°F). However, brace yourself for some rain, as the area receives an average of 418 mm (16.5 in) of precipitation over 29 days, all while maintaining a cozy average humidity level of 82%.

September Temperature in San Sebastian

In September in San Sebastian, the average temperature is 26°C (80°F), with maximums that can reach 34°C (93°F) and minimums as low as 21°C (71°F). This warm and pleasant weather makes San Sebastian an ideal destination for travelers seeking a comfortable climate.

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

The chart illustrates September 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, September typically has an average temperature of 26°C (80°F), with highs reaching up to 34°C (93°F) and lows dropping to around 21°C (71°F).
JanFebMarAprMayJunJulAugSepOctNovDec798082828180818079798079
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.

September Precipitation in San Sebastian

In San Sebastian in September, the total precipitation amount is 418 mm (16.5 in) spread over a duration of 29 days.

September Precipitation Trends in San Sebastian

The chart displays monthly precipitation patterns in San Sebastian, with values for each month alongside September’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how September’s conditions compare to those of other months. In San Sebastian, September typically receives around 418 mm (16.5 inches) of precipitation spread over approximately 29 days.
JanFebMarAprMayJunJulAugSepOctNovDec24184410544737329236241837810626
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in San Sebastian

In San Sebastian in September, humidity is 82%. With an average temperature of 26°C (80°F), this humidity feels like a heavy, warm blanket wrapping around you, making outdoor activities feel more exhausting and sweaty, which can be quite challenging for traveling.

September Average Humidity in San Sebastian

This chart illustrates the average monthly humidity levels in San Sebastian, with September’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In September, average humidity in San Sebastian is approximately 82%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec76%68%59%57%65%66%75%82%82%83%80%76%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in San Sebastian

In San Sebastian in September, the maximum UV index reaches 13, which corresponds to an extreme Exposure Category. With a time to burn of just 10 minutes, it's crucial to take protective measures. For detailed information, you can check the Hourly UV Index in San Sebastian.

Maximum UV Index Levels in San Sebastian for September

The chart shows the monthly maximum UV Index (UVI) for San Sebastian in September, 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 September, the maximum UV index in San Sebastian typically reaches 13, which falls under the extreme exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec1011131413131312131299
Data source: San Sebastian September 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 September 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 September’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 September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather26°C (79°F)24 mm (1.0 inches)76%very high
February Weather27°C (81°F)18 mm (0.7 inches)68%extreme
March Weather28°C (82°F)44 mm (1.7 inches)59%extreme
April Weather28°C (83°F)105 mm (4.1 inches)57%extreme
May Weather27°C (81°F)447 mm (17.6 inches)65%extreme
June Weather27°C (80°F)373 mm (14.7 inches)66%extreme
July Weather27°C (81°F)292 mm (11.5 inches)75%extreme
August Weather27°C (80°F)362 mm (14.3 inches)82%extreme
September Weather26°C (80°F)418 mm (16.5 inches)82%extreme
October Weather26°C (79°F)378 mm (14.9 inches)83%extreme
November Weather27°C (80°F)106 mm (4.2 inches)80%very high
December Weather26°C (80°F)26 mm (1.0 inches)76%very high

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