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September Weather in Bay Saint Louis, United States

Last updated: August 27, 2025

In Bay Saint Louis, United States, the average temperature in September is a pleasant 27°C (80°F). Expect a minimum of 18°C (65°F) and a maximum of 33°C (91°F) during this time. Rainfall is quite frequent, with 155 mm (6.1 in) of precipitation over about 14 days. Additionally, the average humidity hovers around 80%, creating a warm and humid environment.

September Temperature in Bay Saint Louis

In September in Bay Saint Louis, the average temperature is 27°C (80°F). The maximum can reach 33°C (91°F), and the minimum can be as low as 18°C (65°F). It's an ideal time for travelers looking to enjoy warm weather with comfortable evenings.

September Weather in Bay Saint Louis: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Bay Saint Louis, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Bay Saint Louis, September typically has an average temperature of 27°C (80°F), with highs reaching up to 33°C (91°F) and lows dropping to around 18°C (65°F).
JanFebMarAprMayJunJulAugSepOctNovDec545864697681828280746357
Data source: Temperature data for Bay Saint Louis 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 Bay Saint Louis

In Bay Saint Louis in September, the precipitation amount is 155 mm (6.1 in) over the course of 14 days.

September Precipitation Trends in Bay Saint Louis

The chart displays monthly precipitation patterns in Bay Saint Louis, 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 Bay Saint Louis, September typically receives around 155 mm (6.1 inches) of precipitation spread over approximately 14 days.
JanFebMarAprMayJunJulAugSepOctNovDec1071228912613827920024015613359120
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Bay Saint Louis

In Bay Saint Louis in September humidity is 80%. With an average temperature of 27°C (80°F), this humidity feels like a warm, heavy blanket enveloping you, making outdoor activities feel more exhausting and sticky, and challenging you to stay hydrated while exploring.

September Average Humidity in Bay Saint Louis

This chart illustrates the average monthly humidity levels in Bay Saint Louis, 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 Bay Saint Louis is approximately 80%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec82%80%80%78%73%71%79%78%80%76%83%87%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Bay Saint Louis

In Bay Saint Louis in September, the maximum UV index reaches 10, which corresponds to a very high Exposure Category. With a time to burn of just 15 minutes, it's crucial to take precautions. For more detailed information, you can check the Hourly UV Index in Bay Saint Louis.

Maximum UV Index Levels in Bay Saint Louis for September

The chart shows the monthly maximum UV Index (UVI) for Bay Saint Louis 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 Bay Saint Louis typically reaches 10, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec589111111121110864
Data source: Bay Saint Louis 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 Bay Saint Louis Compares to Other Months

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

This table compares monthly weather conditions in Bay Saint Louis, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather12°C (54°F)107 mm (4.2 inches)82%moderate
February Weather15°C (59°F)122 mm (4.8 inches)80%very high
March Weather18°C (64°F)89 mm (3.5 inches)80%very high
April Weather20°C (69°F)126 mm (4.9 inches)78%extreme
May Weather24°C (76°F)138 mm (5.4 inches)73%extreme
June Weather27°C (81°F)279 mm (11.0 inches)71%extreme
July Weather28°C (82°F)200 mm (7.9 inches)79%extreme
August Weather28°C (83°F)239 mm (9.4 inches)78%extreme
September Weather27°C (80°F)155 mm (6.1 inches)80%very high
October Weather23°C (75°F)133 mm (5.2 inches)76%very high
November Weather17°C (63°F)59 mm (2.3 inches)83%high
December Weather14°C (58°F)120 mm (4.7 inches)87%moderate

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