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September Weather in Saint Marys, United States

Last updated: June 24, 2025

In September, the average temperature in Saint Marys, United States is 22°C (72°F), offering a pleasant climate. Expect temperatures to range from a chilly 6°C (43°F) to a sizzling 36°C (96°F). While enjoying the mild weather, you might encounter 80 mm (3.1 in) of precipitation over approximately 8 days, contributing to an average humidity of 71%.

September Temperature in Saint Marys

In September in Saint Marys, the average temperature is 22°C (72°F). Maximum temperatures can reach 36°C (96°F), while minimum temperatures can drop as low as 6°C (43°F). This range makes it an ideal time for travelers seeking pleasant weather and a variety of outdoor activities.

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 22°C (72°F), with highs reaching up to 36°C (96°F) and lows dropping to around 6°C (43°F).
JanFebMarAprMayJunJulAugSepOctNovDec313246546577817772564437
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 80 mm (3.1 in) over a period of 8 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 80 mm (3.1 inches) of precipitation spread over approximately 8 days.
JanFebMarAprMayJunJulAugSepOctNovDec382793782059690130801093330
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 71%. With an average temperature of 22°C (72°F), this humidity feels like the air is thick and slightly stifling, making outdoor activities require frequent breaks to stay hydrated and cool.

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 71%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec76%78%70%73%82%82%81%78%71%71%81%84%
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 9, which corresponds to a very high Exposure Category. The time to burn is just 15 minutes, so it's essential to take precautions. For detailed information, you can check 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 9, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec3569101111109643
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 Weather-1°C (31°F)38 mm (1.5 inches)76%moderate
February Weather0°C (32°F)27 mm (1.1 inches)77%moderate
March Weather8°C (46°F)93 mm (3.7 inches)70%high
April Weather12°C (54°F)78 mm (3.1 inches)73%very high
May Weather19°C (66°F)205 mm (8.1 inches)82%very high
June Weather25°C (78°F)96 mm (3.8 inches)82%extreme
July Weather27°C (81°F)90 mm (3.6 inches)81%extreme
August Weather25°C (77°F)130 mm (5.1 inches)78%very high
September Weather22°C (72°F)80 mm (3.1 inches)71%very high
October Weather13°C (57°F)109 mm (4.3 inches)71%high
November Weather6°C (44°F)32 mm (1.3 inches)81%moderate
December Weather3°C (37°F)30 mm (1.2 inches)84%moderate

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