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September Weather in St Martin, Guernsey

Last updated: August 23, 2025

In September, the average temperature in St Martin, Guernsey is a comfortable 17°C (62°F), with lows dipping to 12°C (54°F) and highs reaching up to 21°C (71°F). Expect around 63 mm (2.5 in) of precipitation over approximately 9 days, and a pleasant average humidity of 76%.

September Temperature in St Martin

In September in St Martin, the average temperature is 17°C (62°F). Maximums can reach 21°C (71°F), and minimums can be as low as 12°C (54°F). This mild climate makes St Martin an ideal destination for travelers looking to enjoy comfortable weather.

September Weather in St Martin: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in St Martin, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In St Martin, September typically has an average temperature of 17°C (62°F), with highs reaching up to 21°C (71°F) and lows dropping to around 12°C (54°F).
JanFebMarAprMayJunJulAugSepOctNovDec484848505458616362595451
Data source: Temperature data for St Martin 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 St Martin

In St Martin in September, the total precipitation amount is 63 mm (2.5 in) spread over a duration of 9 days.

September Precipitation Trends in St Martin

The chart displays monthly precipitation patterns in St Martin, 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 St Martin, September typically receives around 63 mm (2.5 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec948673345559375063144126163
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in St Martin

In St Martin in September, humidity is 76%. With an average temperature of 17°C (62°F), this humidity feels like a warm, enveloping embrace, making travel feel slightly more challenging as it can lead to a sticky discomfort, especially during outdoor excursions.

September Average Humidity in St Martin

This chart illustrates the average monthly humidity levels in St Martin, 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 St Martin is approximately 76%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec89%88%85%84%81%77%63%71%76%89%90%90%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in St Martin

In St Martin in September, the maximum UV index is 6, which corresponds to a high Exposure Category. The time to burn is approximately 25 minutes. To find the hourly UV index in St Martin, you can refer to this Hourly UV Index in St Martin.

Maximum UV Index Levels in St Martin for September

The chart shows the monthly maximum UV Index (UVI) for St Martin 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 St Martin typically reaches 6, which falls under the high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec234679876421
Data source: St Martin 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 St Martin Compares to Other Months

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

This table compares monthly weather conditions in St Martin, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather9°C (49°F)94 mm (3.7 inches)89%low
February Weather9°C (48°F)86 mm (3.4 inches)88%moderate
March Weather9°C (49°F)73 mm (2.9 inches)85%moderate
April Weather10°C (50°F)34 mm (1.3 inches)84%high
May Weather12°C (54°F)55 mm (2.2 inches)81%high
June Weather14°C (58°F)59 mm (2.3 inches)77%very high
July Weather16°C (62°F)37 mm (1.5 inches)63%very high
August Weather17°C (63°F)50 mm (2.0 inches)71%high
September Weather17°C (62°F)63 mm (2.5 inches)76%high
October Weather15°C (59°F)144 mm (5.7 inches)89%moderate
November Weather12°C (54°F)126 mm (5.0 inches)90%low
December Weather11°C (51°F)163 mm (6.4 inches)90%low

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