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September Weather in Saint Lawrence, United States

Last updated: June 24, 2025

In September, the average temperature in Saint Lawrence, United States hovers around 21°C (70°F). However, temperatures can swing between a cool 4°C (39°F) and a sizzling 34°C (94°F). Expect about 100 mm (3.9 in) of precipitation spread across 10 days, and enjoy a pleasant average humidity level of 66%.

September Temperature in Saint Lawrence

In September in Saint Lawrence, the average temperature is 21°C (70°F). Maximums can reach up to 34°C (94°F), while minimums can dip as low as 4°C (39°F). Pack for varied weather to ensure a comfortable travel experience.

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

The chart illustrates September temperature patterns in Saint Lawrence, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Saint Lawrence, September typically has an average temperature of 21°C (70°F), with highs reaching up to 34°C (94°F) and lows dropping to around 4°C (39°F).
JanFebMarAprMayJunJulAugSepOctNovDec343742536372787569594437
Data source: Temperature data for Saint Lawrence 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 Lawrence

In Saint Lawrence in September, the precipitation amount is 100 mm (3.9 in) over a span of 10 days.

September Precipitation Trends in Saint Lawrence

The chart displays monthly precipitation patterns in Saint Lawrence, 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 Lawrence, September typically receives around 100 mm (3.9 inches) of precipitation spread over approximately 10 days.
JanFebMarAprMayJunJulAugSepOctNovDec671051031031361091411511001018799
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Saint Lawrence

In Saint Lawrence in September humidity is 66%. With an average temperature of 21°C (70°F), this humidity feels like a warm embrace, making it comfortable for leisurely strolls but slightly sticky for longer excursions.

September Average Humidity in Saint Lawrence

This chart illustrates the average monthly humidity levels in Saint Lawrence, 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 Lawrence is approximately 66%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec87%85%85%83%75%74%65%62%66%79%87%85%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Saint Lawrence

In Saint Lawrence 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 Lawrence.

Maximum UV Index Levels in Saint Lawrence for September

The chart shows the monthly maximum UV Index (UVI) for Saint Lawrence 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 Lawrence typically reaches 8, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec356910101098642
Data source: Saint Lawrence 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 Lawrence Compares to Other Months

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

This table compares monthly weather conditions in Saint Lawrence, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather1°C (34°F)67 mm (2.6 inches)87%moderate
February Weather3°C (37°F)105 mm (4.1 inches)85%moderate
March Weather6°C (42°F)103 mm (4.1 inches)85%high
April Weather12°C (53°F)103 mm (4.0 inches)83%very high
May Weather17°C (63°F)136 mm (5.3 inches)75%very high
June Weather22°C (72°F)109 mm (4.3 inches)73%very high
July Weather25°C (78°F)141 mm (5.5 inches)65%very high
August Weather24°C (75°F)151 mm (5.9 inches)62%very high
September Weather21°C (70°F)100 mm (3.9 inches)66%very high
October Weather15°C (59°F)101 mm (4.0 inches)79%high
November Weather7°C (45°F)87 mm (3.4 inches)87%moderate
December Weather3°C (38°F)99 mm (3.9 inches)85%low

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