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September Weather in San Luis, United States

Last updated: June 24, 2025

In September, the average temperature in San Luis, United States hovers around 14°C (57°F), with a minimum of -6°C (21°F) and a maximum of 29°C (84°F). Expect about 31 mm (1.2 in) of precipitation spread across 6 days, and enjoy an average humidity level of 70%.

September Temperature in San Luis

In September in San Luis, the average temperature is 14°C (57°F), with maximums reaching up to 29°C (84°F) and minimums dropping as low as -6°C (21°F). Travelers should be prepared for a wide range of temperatures and enjoy both warm and cool experiences during their visit.

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

The chart illustrates September temperature patterns in San Luis, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In San Luis, September typically has an average temperature of 14°C (57°F), with highs reaching up to 29°C (84°F) and lows dropping to around -6°C (21°F).
JanFebMarAprMayJunJulAugSepOctNovDec222534415161646357453525
Data source: Temperature data for San Luis 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 Luis

In San Luis in September, the precipitation amount is 31 mm (1.2 in) over a span of 6 days.

September Precipitation Trends in San Luis

The chart displays monthly precipitation patterns in San Luis, 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 Luis, September typically receives around 31 mm (1.2 inches) of precipitation spread over approximately 6 days.
JanFebMarAprMayJunJulAugSepOctNovDec232537354228714531271723
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in San Luis

In San Luis in September, humidity is 70%. With an average temperature of 14°C (57°F), this humidity feels like a damp blanket wrapping around you, making travel slightly uncomfortable as the air feels heavier and every step seems more laborious.

September Average Humidity in San Luis

This chart illustrates the average monthly humidity levels in San Luis, 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 Luis is approximately 70%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec84%84%75%68%62%55%54%61%70%78%81%85%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in San Luis

In San Luis in September, the maximum UV index reaches 11, which corresponds to an extreme Exposure Category. With a time to burn of just 10 minutes, it's essential to take precautions. For more details, you can check the Hourly UV Index in San Luis.

Maximum UV Index Levels in San Luis for September

The chart shows the monthly maximum UV Index (UVI) for San Luis 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 Luis typically reaches 11, which falls under the extreme exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec4710111213131211854
Data source: San Luis 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 Luis Compares to Other Months

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

This table compares monthly weather conditions in San Luis, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-5°C (23°F)23 mm (0.9 inches)84%moderate
February Weather-4°C (25°F)25 mm (1.0 inches)84%high
March Weather1°C (34°F)37 mm (1.5 inches)74%very high
April Weather5°C (42°F)35 mm (1.4 inches)68%extreme
May Weather10°C (51°F)42 mm (1.6 inches)62%extreme
June Weather16°C (62°F)28 mm (1.1 inches)55%extreme
July Weather18°C (65°F)71 mm (2.8 inches)54%extreme
August Weather17°C (63°F)45 mm (1.8 inches)61%extreme
September Weather14°C (57°F)31 mm (1.2 inches)70%extreme
October Weather7°C (45°F)27 mm (1.1 inches)78%very high
November Weather2°C (35°F)17 mm (0.7 inches)81%moderate
December Weather-4°C (25°F)23 mm (0.9 inches)85%moderate

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