September weather forecast
Saint Helena Island, Saint Helena, Ascension and Tristan da Cunha

September ushers in slightly warmer temperatures, signaling the transition from winter to spring. The slight increase in temperature is balanced by the reduction in rainfall and consistent daylight hours. An average sea temperature of about 21°C (69.8°F) and the UV index rising to 11 indicates a gradual return to sunnier days. Given these weather changes, wildlife activity is palpable and diverse in September. Fashioned by nature's hand, September offers unparalleled beauty to visitors, highlighted by the hybrid weather conditions.

Temperature

Saint Helena Island registers an average high-temperature of a still comfortable 18°C (64.4°F) at the commencement of September, closely related to the preceding month. Saint Helena Island registers a subtle dip to an average of 15°C (59°F) during the nights of September.

Rainfall

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. In Saint Helena Island, Saint Helena, Ascension and Tristan da Cunha, during the entire year, the rain falls for 170 days and collects up to 748mm (29.45") of precipitation.

Sea temperature

In September, the average sea temperature is 21°C (69.8°F).
Note: For most individuals, swimming in 21°C (69.8°F) is not a pleasurable activity. Breathing becomes progressively more difficult as water temperature declines below 21°C (69.8°F).

Daylight

In September, the average length of the day is 12h and 1min.
On the first day of the month, sunrise is at 06:28 and sunset at 18:17. On the last day of September, in Saint Helena Island, sunrise is at 06:05 and sunset at 18:19 GMT.

Sunshine

September and December, with an average of 12h of sunshine, are months with the least sunshine in Saint Helena Island.

UV index

The average daily maximum UV index in September is 11. A UV Index value of 11, and more, symbolizes an ultimate health vulnerability from unprotected exposure to Sun's UV rays for the ordinary person.
Note: The UV index of 11 during September leads to these advisories:
Enforce all necessary precautions, unprotected skin might burn swiftly. Limit direct sun exposure especially between 10 a.m. and 4 p.m., when UV radiation is at its peak. However, keep in mind that shade structures may not provide full sun protection. Sun-related eye harm can be minimized with proper sunglasses offering UVA and UVB coverage.