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September Weather in Santiago, Mexico

Last updated: August 27, 2025

In September, the average temperature in Santiago, Mexico hovers around 18°C (65°F), offering a pleasant climate. Expect temperatures to range from a chilly 9°C (49°F) at their lowest to a warm 28°C (83°F) at their peak. Be prepared for some rain, as precipitation averages around 100 mm (3.9 in) over 12 days of the month, accompanied by a relatively high humidity level of 81%.

September Temperature in Santiago

In September in Santiago, the average temperature is 18°C (65°F). Maximums can reach 28°C (83°F) and minimums can be as low as 9°C (49°F). This mild weather makes Santiago a perfect destination for travelers looking to enjoy comfortable outdoor activities.

September Weather in Santiago: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Santiago, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Santiago, September typically has an average temperature of 18°C (65°F), with highs reaching up to 28°C (83°F) and lows dropping to around 9°C (49°F).
JanFebMarAprMayJunJulAugSepOctNovDec545863677068666764625854
Data source: Temperature data for Santiago 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 Santiago

In Santiago in September, the precipitation amount is 100 mm (3.9 in) over the course of 12 days.

September Precipitation Trends in Santiago

The chart displays monthly precipitation patterns in Santiago, 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 Santiago, September typically receives around 100 mm (3.9 inches) of precipitation spread over approximately 12 days.
JanFebMarAprMayJunJulAugSepOctNovDec1210131041998956100501510
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Santiago

In Santiago in September, humidity is 81%. With an average temperature of 18°C (65°F), this humidity feels like a thick blanket wrapping around you, making every step feel heavier and the air thick and sultry—a challenging environment for traveling.

September Average Humidity in Santiago

This chart illustrates the average monthly humidity levels in Santiago, 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 Santiago is approximately 81%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec75%69%65%64%75%78%67%64%82%86%87%87%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Santiago

In Santiago in September, the maximum UV index is 14, which corresponds to an extreme Exposure Category. The time to burn is just 10 minutes, so it's crucial to take precautions. For the detailed hourly UV index in Santiago, you can check here.

Maximum UV Index Levels in Santiago for September

The chart shows the monthly maximum UV Index (UVI) for Santiago 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 Santiago typically reaches 14, which falls under the extreme exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec9111415151414141412108
Data source: Santiago 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 Santiago Compares to Other Months

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

This table compares monthly weather conditions in Santiago, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather12°C (54°F)12 mm (0.5 inches)75%very high
February Weather15°C (59°F)10 mm (0.4 inches)69%extreme
March Weather17°C (63°F)13 mm (0.5 inches)65%extreme
April Weather19°C (67°F)10 mm (0.4 inches)64%extreme
May Weather21°C (70°F)41 mm (1.6 inches)75%extreme
June Weather20°C (68°F)99 mm (3.9 inches)78%extreme
July Weather19°C (67°F)89 mm (3.5 inches)67%extreme
August Weather19°C (67°F)56 mm (2.2 inches)64%extreme
September Weather18°C (65°F)100 mm (3.9 inches)81%extreme
October Weather17°C (62°F)50 mm (2.0 inches)85%extreme
November Weather14°C (58°F)14 mm (0.6 inches)87%very high
December Weather12°C (55°F)10 mm (0.4 inches)87%very high

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