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September Weather in Saint Marys, United States

Last updated: June 24, 2025

In Saint Marys, United States, the average temperature in September reaches a pleasant 21°C (70°F). Expect a range of 5°C (42°F) to a warm 36°C (98°F), making it ideal for various activities. However, be prepared for some rain, as the area sees about 111 mm (4.4 in) of precipitation over 9 days. With an average humidity of 73%, the atmosphere tends to be quite refreshing!

September Temperature in Saint Marys

In September in Saint Marys, the average temperature is 21°C (70°F). Maximums can reach 36°C (98°F) and minima can be as low as 5°C (42°F). This range makes it essential for travelers to pack appropriately to enjoy the diverse weather conditions.

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

The chart illustrates September temperature patterns in Saint Marys, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Saint Marys, September typically has an average temperature of 21°C (70°F), with highs reaching up to 36°C (98°F) and lows dropping to around 5°C (42°F).
JanFebMarAprMayJunJulAugSepOctNovDec333845546471767469594438
Data source: Temperature data for Saint Marys 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 Saint Marys

In Saint Marys in September, the precipitation amount is 111 mm (4.4 in) over the course of 9 days.

September Precipitation Trends in Saint Marys

The chart displays monthly precipitation patterns in Saint Marys, 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 Saint Marys, September typically receives around 111 mm (4.4 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec9512711715115018013411011111788119
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Saint Marys

In Saint Marys in September, humidity is 73%. With an average temperature of 21°C (70°F), this humidity feels like a warm embrace that can make outdoor activities feel sweltering, so it's essential to stay hydrated and take breaks in the shade while exploring.

September Average Humidity in Saint Marys

This chart illustrates the average monthly humidity levels in Saint Marys, 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 Saint Marys is approximately 73%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec88%88%88%87%82%84%82%73%74%81%89%86%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Saint Marys

In Saint Marys in September, the maximum UV index is 8, which corresponds to a very high Exposure Category. This means that the time to burn is only 15 minutes. For more detailed information, you can refer to the Hourly UV Index in Saint Marys.

Maximum UV Index Levels in Saint Marys for September

The chart shows the monthly maximum UV Index (UVI) for Saint Marys 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 Saint Marys typically reaches 8, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec357910101098643
Data source: Saint Marys 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 Saint Marys Compares to Other Months

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

This table compares monthly weather conditions in Saint Marys, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather1°C (34°F)95 mm (3.7 inches)88%moderate
February Weather3°C (38°F)127 mm (5.0 inches)88%moderate
March Weather7°C (45°F)117 mm (4.6 inches)88%high
April Weather12°C (54°F)151 mm (6.0 inches)86%very high
May Weather18°C (65°F)150 mm (5.9 inches)82%very high
June Weather22°C (72°F)180 mm (7.1 inches)84%very high
July Weather24°C (76°F)134 mm (5.3 inches)82%very high
August Weather23°C (74°F)110 mm (4.3 inches)73%very high
September Weather21°C (70°F)111 mm (4.4 inches)73%very high
October Weather15°C (59°F)117 mm (4.6 inches)81%high
November Weather7°C (44°F)88 mm (3.5 inches)89%moderate
December Weather4°C (39°F)119 mm (4.7 inches)86%moderate

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