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September Weather in San Francisco, El Salvador

Last updated: August 23, 2025

In September, the average temperature in San Francisco, El Salvador is a warm 26°C (78°F). Expect temperatures to vary, with a minimum of 20°C (68°F) and a maximum soaring to 36°C (97°F). However, prepare for some rain, as the area receives an average precipitation of 295 mm (11.6 in) over 27 days. With an average humidity of 77%, the air will feel quite tropical!

September Temperature in San Francisco

In September in San Francisco, the average temperature is 26°C (78°F). Maximums can reach 36°C (97°F), while minimums can drop to as low as 20°C (68°F). It's a great time to enjoy outdoor activities while staying hydrated and prepared for warm weather.

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

The chart illustrates September temperature patterns in San Francisco, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In San Francisco, September typically has an average temperature of 26°C (78°F), with highs reaching up to 36°C (97°F) and lows dropping to around 20°C (68°F).
JanFebMarAprMayJunJulAugSepOctNovDec788082828079818078777777
Data source: Temperature data for San Francisco 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 Francisco

In San Francisco in September, the precipitation amount is 295 mm (11.6 in) distributed over 27 days.

September Precipitation Trends in San Francisco

The chart displays monthly precipitation patterns in San Francisco, 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 Francisco, September typically receives around 295 mm (11.6 inches) of precipitation spread over approximately 27 days.
JanFebMarAprMayJunJulAugSepOctNovDec2265533226797234295335644
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in San Francisco

In San Francisco in September, humidity is 77%. With an average temperature of 26°C (78°F), this humidity feels like an inviting embrace that can quickly fatigue travelers, making every step feel heavier and each breath a reminder of the warm, moist air surrounding them.

September Average Humidity in San Francisco

This chart illustrates the average monthly humidity levels in San Francisco, 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 Francisco is approximately 77%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec63%62%59%59%59%68%78%79%77%77%75%67%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in San Francisco

In San Francisco 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 Francisco.

Maximum UV Index Levels in San Francisco for September

The chart shows the monthly maximum UV Index (UVI) for San Francisco 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 Francisco typically reaches 13, which falls under the extreme exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec11121414141413131313109
Data source: San Francisco 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 Francisco Compares to Other Months

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

This table compares monthly weather conditions in San Francisco, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather26°C (78°F)2 mm (0.1 inches)63%extreme
February Weather27°C (80°F)2 mm (0.1 inches)62%extreme
March Weather28°C (83°F)6 mm (0.2 inches)59%extreme
April Weather28°C (83°F)55 mm (2.2 inches)59%extreme
May Weather27°C (80°F)332 mm (13.1 inches)59%extreme
June Weather26°C (79°F)267 mm (10.5 inches)68%extreme
July Weather27°C (81°F)97 mm (3.8 inches)77%extreme
August Weather26°C (80°F)234 mm (9.2 inches)79%extreme
September Weather26°C (78°F)295 mm (11.6 inches)77%extreme
October Weather25°C (77°F)335 mm (13.2 inches)77%extreme
November Weather25°C (77°F)64 mm (2.5 inches)75%very high
December Weather25°C (77°F)4 mm (0.2 inches)66%very high

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