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September Weather in Saint-Thomas, Canada

Last updated: June 18, 2025

In Saint-Thomas, Canada, the average temperature in September is a comfortable 16°C (60°F), with daily highs reaching up to 31°C (89°F) and the occasional drop to a chilly 1°C (33°F). Expect about 64 mm (2.5 in) of precipitation spread over 9 days, contributing to a 78% average humidity that can make the air feel quite moist.

September Temperature in Saint-Thomas

In September in Saint-Thomas, the average temperature is 16°C (60°F), with maximums reaching 31°C (89°F) and minimums dropping as low as 1°C (33°F). This varied climate makes it an ideal destination for travelers looking to experience a wide range of temperatures.

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

The chart illustrates September temperature patterns in Saint-Thomas, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Saint-Thomas, September typically has an average temperature of 16°C (60°F), with highs reaching up to 31°C (89°F) and lows dropping to around 1°C (33°F).
JanFebMarAprMayJunJulAugSepOctNovDec151827415665716960483321
Data source: Temperature data for Saint-Thomas 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-Thomas

In Saint-Thomas in September, the precipitation amount is 64 mm (2.5 in) over a span of 9 days.

September Precipitation Trends in Saint-Thomas

The chart displays monthly precipitation patterns in Saint-Thomas, 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-Thomas, September typically receives around 64 mm (2.5 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec8382851219695891046412411490
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Saint-Thomas

In Saint-Thomas in September humidity is 78%. With an average temperature of 16°C (60°F), this humidity feels like a damp embrace, making travel a bit uncomfortable as the air clings to your skin and leaves you feeling sticky.

September Average Humidity in Saint-Thomas

This chart illustrates the average monthly humidity levels in Saint-Thomas, 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-Thomas is approximately 78%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec93%92%86%85%80%74%76%75%78%86%89%89%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Saint-Thomas

In Saint-Thomas 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-Thomas.

Maximum UV Index Levels in Saint-Thomas for September

The chart shows the monthly maximum UV Index (UVI) for Saint-Thomas 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-Thomas typically reaches 7, which falls under the high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec245799887532
Data source: Saint-Thomas 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-Thomas Compares to Other Months

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

This table compares monthly weather conditions in Saint-Thomas, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-9°C (15°F)83 mm (3.3 inches)93%low
February Weather-8°C (18°F)82 mm (3.2 inches)92%moderate
March Weather-3°C (27°F)85 mm (3.4 inches)86%moderate
April Weather5°C (42°F)121 mm (4.8 inches)85%high
May Weather13°C (56°F)96 mm (3.8 inches)80%very high
June Weather19°C (66°F)95 mm (3.7 inches)74%very high
July Weather22°C (71°F)89 mm (3.5 inches)76%very high
August Weather20°C (69°F)104 mm (4.1 inches)75%very high
September Weather16°C (60°F)64 mm (2.5 inches)78%high
October Weather9°C (49°F)124 mm (4.9 inches)86%moderate
November Weather0°C (33°F)114 mm (4.5 inches)88%moderate
December Weather-6°C (21°F)90 mm (3.5 inches)89%low

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