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September Weather in San Francisco, Peru

Last updated: August 27, 2025

In San Francisco, Peru, the average temperature in September hovers around 15°C (60°F). Expect cooler nights as temperatures can drop to a minimum of 7°C (45°F), while daytime highs may reach up to 24°C (76°F). It's a relatively wet month with an average precipitation of 189 mm (7.5 in) spread over 18 days, alongside a comfortable average humidity of 52%.

September Temperature in San Francisco

In September in San Francisco, the average temperature is 15°C (60°F). Maximums can reach 24°C (76°F), and minimums can drop to as low as 7°C (45°F). This mild weather makes it an ideal time for outdoor adventures and exploring the local sights.

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 15°C (60°F), with highs reaching up to 24°C (76°F) and lows dropping to around 7°C (45°F).
JanFebMarAprMayJunJulAugSepOctNovDec616161605959585859616261
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 total precipitation amount is 189 mm (7.5 in) over the course of 18 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 189 mm (7.5 inches) of precipitation spread over approximately 18 days.
JanFebMarAprMayJunJulAugSepOctNovDec408401465282105402764189299325325
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 52%. With an average temperature of 15°C (60°F), this humidity feels like a refreshing embrace for traveling, making outdoor exploration enjoyable without feeling overly sticky or uncomfortable.

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 52%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec93%92%92%90%85%70%55%44%52%65%81%89%
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 an alarming 15, which falls into the extreme Exposure Category. With a time to burn of just 10 minutes, it's crucial to take precautions. 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 15, which falls under the extreme exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec171717161311121315171716
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 Weather16°C (61°F)408 mm (16.0 inches)93%extreme
February Weather16°C (61°F)401 mm (15.8 inches)92%extreme
March Weather16°C (61°F)465 mm (18.3 inches)92%extreme
April Weather16°C (61°F)282 mm (11.1 inches)90%extreme
May Weather15°C (60°F)105 mm (4.1 inches)85%extreme
June Weather15°C (59°F)40 mm (1.6 inches)70%extreme
July Weather14°C (58°F)27 mm (1.1 inches)54%extreme
August Weather15°C (58°F)64 mm (2.5 inches)44%extreme
September Weather15°C (60°F)189 mm (7.5 inches)52%extreme
October Weather16°C (61°F)299 mm (11.8 inches)65%extreme
November Weather16°C (62°F)325 mm (12.8 inches)81%extreme
December Weather16°C (62°F)325 mm (12.8 inches)89%extreme

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