September weather forecast
Saint Helena, Ascension and Tristan da Cunha

September brings the onset of spring to the islands of Saint Helena, Ascension, and Tristan da Cunha, heralding warmer temperatures and changes in precipitation patterns.

In Saint Helena, September is characterised by rising temperatures, typically ranging from 15°C (59°F) to 23°C (73.4°F), as the island transitions fully into the spring season. Rainfall continues to increase compared to August, signalling a departure from the dry season. The capital, Jamestown, reflects these climate patterns. As the island moves from September to October, both temperatures and rainfall are expected to increase further.

On Ascension Island, September sees a slight rise in temperatures, with values typically ranging from 23°C (73.4°F) to 30°C (86°F). Rainfall also increases compared to August, marking a transition towards the wet season. Georgetown, the main settlement on Ascension Island, experiences similar weather conditions. As the island progresses into October, both temperatures and rainfall are expected to increase.

Tristan da Cunha in September witnesses a rise in temperatures, typically fluctuating between 11°C (51.8°F) and 16°C (60.8°F). Rainfall decreases slightly compared to August, yet it remains significant due to the island's oceanic climate. Edinburgh of the Seven Seas, the main settlement, aligns with these weather conditions. Transitioning from September to October, a further increase in temperature is expected, while rainfall remains relatively consistent.

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• Jamestown - September »
  July through September, when the average high-temperature reaches 22°C (71.6°F), are the coldest months. In September, in Jamestown the rain falls for 2 days.
• Georgetown - September »
  September is the month that records the lowest temperatures in Georgetown with averages ranging from a high of 23.5°C (74.3°F) to a low of 23°C (73.4°F). In Georgetown in September, during 18.5 rainfall days, 14mm (0.55") of precipitation is typically accumulated.
• Longwood - September »
  May, September through November are months with the least rain in Longwood when the rain falls for 9.6 days and typically aggregates up to 6mm (0.24") of rain. September temperatures in Longwood vary between a high-temperature of 19.7°C (67.5°F) and a low-temperature of 18.7°C (65.7°F).
• Tristan da Cunha - September »
  In Tristan da Cunha in September, it is raining for 24 days, with typically 169mm (6.65") of accumulated precipitation. In Tristan da Cunha the average length of the day in September is 11h and 52min.
• Ascension Island - September »
  On the last day of September, in Ascension Island sunrise is at 06:42 and sunset at 18:52 GMT. September and October, with an average sea temperature of 24°C (75.2°F), are months with the coldest seawater in Ascension Island.
• Saint Helena Island - September »
  In Saint Helena Island in September, during 12 rainfall days, 54mm (2.13") of precipitation is typically accumulated. In Saint Helena Island, Saint Helena, Ascension and Tristan da Cunha, in September, during 12 rainfall days, 54mm (2.13") of precipitation is typically accumulated.