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September Weather in Saint Clair, United States

Last updated: June 24, 2025

In September, the average temperature in Saint Clair, United States is a pleasant 19°C (66°F). Visitors can expect a minimum of 4°C (39°F) and a maximum of 32°C (90°F). With an average humidity of 80%, it’s a good idea to prepare for some moisture in the air. Additionally, anticipate around 77 mm (3.0 in) of precipitation spread over 10 days, making it a month of both warmth and occasional rainfall.

September Temperature in Saint Clair

In September in Saint Clair, the average temperature is 19°C (66°F). Maximum temperatures can reach 32°C (90°F), while minimums can drop to as low as 4°C (39°F). This varied climate makes Saint Clair an ideal destination for travelers looking to experience a range of weather conditions.

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

The chart illustrates September temperature patterns in Saint Clair, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Saint Clair, September typically has an average temperature of 19°C (66°F), with highs reaching up to 32°C (90°F) and lows dropping to around 4°C (39°F).
JanFebMarAprMayJunJulAugSepOctNovDec272836455768747266544033
Data source: Temperature data for Saint Clair 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 Clair

In Saint Clair in September, the total precipitation amount is 77 mm (3.0 in) spread over a duration of 10 days.

September Precipitation Trends in Saint Clair

The chart displays monthly precipitation patterns in Saint Clair, 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 Clair, September typically receives around 77 mm (3.0 inches) of precipitation spread over approximately 10 days.
JanFebMarAprMayJunJulAugSepOctNovDec70737097105938280771138263
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Saint Clair

In Saint Clair in September humidity is 80%. With an average temperature of 19°C (66°F), this humidity feels like a warm, thick blanket wrapping around you, making outdoor activities feel more strenuous and sticky, which can ultimately dampen the experience of traveling.

September Average Humidity in Saint Clair

This chart illustrates the average monthly humidity levels in Saint Clair, 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 Clair is approximately 80%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec88%87%85%86%80%80%80%81%80%84%90%86%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Saint Clair

In Saint Clair in September, the maximum UV index is 7, which corresponds to the high Exposure Category. This means that the time to burn is approximately 25 minutes. For more detailed information, you can check the Hourly UV Index in Saint Clair.

Maximum UV Index Levels in Saint Clair for September

The chart shows the monthly maximum UV Index (UVI) for Saint Clair 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 Clair typically reaches 7, which falls under the high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec2458910997542
Data source: Saint Clair 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 Clair Compares to Other Months

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

This table compares monthly weather conditions in Saint Clair, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-3°C (27°F)70 mm (2.8 inches)88%low
February Weather-2°C (29°F)73 mm (2.9 inches)87%moderate
March Weather2°C (36°F)70 mm (2.7 inches)85%moderate
April Weather7°C (46°F)97 mm (3.8 inches)86%very high
May Weather14°C (58°F)105 mm (4.1 inches)80%very high
June Weather20°C (69°F)93 mm (3.6 inches)80%very high
July Weather23°C (74°F)82 mm (3.2 inches)80%very high
August Weather22°C (73°F)80 mm (3.2 inches)80%very high
September Weather19°C (66°F)77 mm (3.0 inches)80%high
October Weather12°C (55°F)113 mm (4.5 inches)84%moderate
November Weather4°C (40°F)82 mm (3.2 inches)89%moderate
December Weather0°C (33°F)63 mm (2.5 inches)86%low

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