September Weather in San Marcos, Mexico

Last updated: August 27, 2025

In September, the average temperature in San Marcos, Mexico hovers around 21°C (70°F), with temperatures ranging from a cool 15°C (59°F) to a warm 30°C (87°F). This month sees an average precipitation of 267 mm (10.5 in) spread over 25 days, contributing to a notably high humidity level of 84%. Perfect weather for enjoying the lush surroundings!

September Temperature in San Marcos

In September in San Marcos, the average temperature is 21°C (70°F), with maximums reaching 30°C (87°F) and minimums dropping as low as 15°C (59°F). This pleasant weather makes it an ideal time for outdoor activities and sightseeing in San Marcos.

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

The chart illustrates September 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, September typically has an average temperature of 21°C (70°F), with highs reaching up to 30°C (87°F) and lows dropping to around 15°C (59°F).

Data source: Temperature data for San Marcos generated using information from the Copernicus Climate Change Service.

September Precipitation in San Marcos

In San Marcos in September, the precipitation amount is 267 mm (10.5 in) over a span of 25 days.

September Precipitation Trends in San Marcos

The chart displays monthly precipitation patterns in San Marcos, 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 Marcos, September typically receives around 267 mm (10.5 inches) of precipitation spread over approximately 25 days.

Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.

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Millimeters (mm) Inches (in)

September Humidity in San Marcos

In San Marcos in September, humidity is 84%. With an average temperature of 21°C (70°F), this humidity feels like thick, warm air wrapping around you, making outdoor activities quite uncomfortable and necessitating frequent hydration breaks for a more enjoyable travel experience.

September Average Humidity in San Marcos

This chart illustrates the average monthly humidity levels in San Marcos, 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 Marcos is approximately 84%, offering insight into how humid the weather typically is during this month.

Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in San Marcos

In San Marcos 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 Marcos.

Maximum UV Index Levels in San Marcos for September

The chart shows the monthly maximum UV Index (UVI) for San Marcos 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 Marcos typically reaches 13, which falls under the extreme exposure category.

Data source: San Marcos 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 Marcos Compares to Other Months

Weather in San Marcos varies notably across the year, with each month offering distinct climate conditions. This page compares September’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 September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	16°C (62°F)	13 mm (0.5 inches)	64%	very high
February Weather	17°C (64°F)	21 mm (0.8 inches)	57%	extreme
March Weather	20°C (68°F)	3 mm (0.1 inches)	46%	extreme
April Weather	21°C (70°F)	1 mm (0.0 inches)	42%	extreme
May Weather	23°C (73°F)	14 mm (0.5 inches)	51%	extreme
June Weather	23°C (73°F)	113 mm (4.4 inches)	74%	extreme
July Weather	21°C (70°F)	252 mm (9.9 inches)	79%	extreme
August Weather	21°C (71°F)	248 mm (9.8 inches)	81%	extreme
September Weather	21°C (70°F)	267 mm (10.5 inches)	84%	extreme
October Weather	21°C (70°F)	99 mm (3.9 inches)	75%	extreme
November Weather	19°C (66°F)	19 mm (0.7 inches)	71%	very high
December Weather	16°C (62°F)	15 mm (0.6 inches)	74%	very high