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September Weather in San Marcos, Peru

Last updated: August 27, 2025

In September, the average temperature in San Marcos, Peru hovers around 4°C (40°F), with minimums dipping to -5°C (24°F) and maximums peaking at 14°C (57°F). Expect a fair amount of moisture, with 114 mm (4.5 in) of precipitation spread over 23 days. Additionally, the region experiences an average humidity of 37%.

September Temperature in San Marcos

In September in San Marcos, the average temperature is 4°C (40°F), with maximums reaching 14°C (57°F) and minimums dropping to as low as -5°C (24°F). Be prepared for chilly weather and pack layers for your trip!

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 4°C (40°F), with highs reaching up to 14°C (57°F) and lows dropping to around -5°C (24°F).
JanFebMarAprMayJunJulAugSepOctNovDec414241414140393940414242
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.

September Precipitation in San Marcos

In San Marcos, in September, the precipitation amount is 114 mm (4.5 in) over a span of 23 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 114 mm (4.5 inches) of precipitation spread over approximately 23 days.
JanFebMarAprMayJunJulAugSepOctNovDec209224272159101514155114179194232
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in San Marcos

In San Marcos in September, humidity is 37%. With an average temperature of 4°C (40°F), this humidity feels like a crisp, brisk chill in the air, making travel refreshing yet invigorating; perfect for bundled walks and sightseeing in the cool atmosphere.

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 37%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec88%86%89%89%86%71%44%34%37%50%73%91%
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 19, which corresponds to an extreme exposure category. With a time to burn of just 10 minutes, it’s essential to take precautions. 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 19, which falls under the extreme exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec212021191613151519191819
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.
 TemperaturePrecipitationHumidityUV
January Weather5°C (42°F)209 mm (8.2 inches)88%extreme
February Weather6°C (42°F)224 mm (8.8 inches)86%extreme
March Weather5°C (42°F)272 mm (10.7 inches)89%extreme
April Weather5°C (42°F)159 mm (6.2 inches)89%extreme
May Weather5°C (41°F)101 mm (4.0 inches)86%extreme
June Weather5°C (41°F)51 mm (2.0 inches)71%extreme
July Weather4°C (39°F)41 mm (1.6 inches)44%extreme
August Weather4°C (40°F)55 mm (2.2 inches)34%extreme
September Weather4°C (40°F)114 mm (4.5 inches)37%extreme
October Weather5°C (41°F)179 mm (7.0 inches)50%extreme
November Weather6°C (42°F)194 mm (7.6 inches)73%extreme
December Weather6°C (42°F)232 mm (9.1 inches)91%extreme

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