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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 hovers around 17°C (63°F), with a minimum drop to 1°C (34°F) and a pleasant peak reaching 31°C (87°F). This month sees about 111 mm (4.4 in) of precipitation spread over 11 days, contributing to an average humidity of 67%. Perfect for those who enjoy a bit of variety in their weather!

September Temperature in Saint Marys

In September in Saint Marys, the average temperature is 17°C (63°F). Maximum temperatures can reach 31°C (87°F), while minimums can dip as low as 1°C (34°F). Be prepared for a wide range of temperatures when traveling to Saint Marys this month!

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 17°C (63°F), with highs reaching up to 31°C (87°F) and lows dropping to around 1°C (34°F).
JanFebMarAprMayJunJulAugSepOctNovDec252936465765706963523831
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), occurring over the course of 11 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 11 days.
JanFebMarAprMayJunJulAugSepOctNovDec9010794124144123117941111259498
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 67%. With an average temperature of 17°C (63°F), this humidity feels like a warm blanket wrapping around you, making travel refreshing yet slightly muggy, as you navigate the sights with a pleasant, if slightly sticky, embrace.

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 67%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec90%90%89%88%80%79%74%64%67%81%89%88%
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.
JanFebMarAprMayJunJulAugSepOctNovDec356910101098642
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-4°C (26°F)90 mm (3.5 inches)89%moderate
February Weather-2°C (29°F)107 mm (4.2 inches)90%moderate
March Weather2°C (36°F)94 mm (3.7 inches)89%high
April Weather8°C (46°F)124 mm (4.9 inches)88%very high
May Weather14°C (58°F)144 mm (5.7 inches)80%very high
June Weather19°C (66°F)123 mm (4.9 inches)79%very high
July Weather21°C (71°F)117 mm (4.6 inches)74%very high
August Weather20°C (69°F)94 mm (3.7 inches)64%very high
September Weather17°C (63°F)111 mm (4.4 inches)67%very high
October Weather11°C (53°F)125 mm (4.9 inches)81%high
November Weather3°C (38°F)94 mm (3.7 inches)89%moderate
December Weather0°C (32°F)98 mm (3.9 inches)88%low

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