September weather forecast
Guernsey

September in Guernsey signals the onset of the autumn season. During this month, the island starts to experience a gradual decline in temperatures, which typically range from 15°C (59°F) to 17°C (62.6°F). Despite this decrease, the weather remains relatively mild and enjoyable for outdoor activities.

Regarding precipitation, September sees an increase compared to the summer months. The island typically receives around 50mm (1.97") of rain, spread over approximately 12 to 15 days. These early autumn showers contribute to a lush landscape, adding to the picturesque beauty of Guernsey during this transitional period.

Compared to August, September presents cooler temperatures and a higher level of rainfall, marking a shift from the summer season. As Guernsey progresses into October, the temperatures continue to fall, and the rainfall levels rise further, fully ushering in the cooler and wetter conditions of the autumn season.

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• Saint Sampson - September »
  As Saint Sampson welcomes September, the average high-temperature stabilizes at a still enjoyable 17.2°C (63°F), showing little deviation from August's 17.8°C (64°F). The months with the highest UV index in Saint Sampson are July through September, with an average maximum UV index of 5.
• Guernsey - September »
  In Guernsey, during September, the rain falls for 13.5 days and regularly aggregates up to 31mm (1.22") of precipitation. On the first day of September in Guernsey sunrise is at 06:27 and sunset at 19:53.
• Saint Peter Port - September »
  July through September, with an average maximum UV index of 5, are months with the highest UV index in Saint Peter Port, Guernsey. In Saint Peter Port, in September, during 13.5 rainfall days, 31mm (1.22") of precipitation is typically accumulated.
• Alderney - September »
  The month with the warmest seawater in Alderney is September, with an average sea temperature of 17.4°C (63.3°F). In Alderney, in September, the average water temperature is 17.4°C (63.3°F).
• Braye du Valle - September »
  In Braye du Valle, during September, the rain falls for 13.5 days and regularly aggregates up to 31mm (1.22") of precipitation. In Braye du Valle, a slight decrease from the daytime peak is noted during the month of September, with an average low-temperature of 15.4°C (59.7°F).
• Fort George - September »
  July through September, with an average maximum UV index of 5, are months with the highest UV index in Fort George, Guernsey. In September, in Fort George the rain falls for 13.5 days.
• Saint Andrew - September »
  The months with the highest UV index in Saint Andrew are July through September, with an average maximum UV index of 5. July through September, with an average maximum UV index of 5, are months with the highest UV index in Saint Andrew, Guernsey.