The climate of St Helena is controlled by the South Atlantic High Pressure Cell and the Equatorial Trough. Despite the island’s locality within the tropics, its climate is kept mild and equable by the South East Trade Winds. The trade winds blow from high to low almost continuously making our weather so changeable, a dull rainy morning can often lead onto a bright sunny afternoon.
The four seasons are not recognised on St Helena, as there are no drastic weather patterns. The hottest months are between January and March. The coldest are between June and September.
For much of the year, temperatures remain between 70-80°F (20-27°C) but nights and early mornings can get colder in the months of June, July and August.
Rains usually fall from late March to early May, with April being the height of the rainy season and again in July to September, with August being the height of this period.
Temperatures in Jamestown range between 20°C – 32°C in the summer and 15°C – 26°C in the winter. The temperatures in the central areas are, on average, 5 – 6 degrees lower, which is why there are noticeable contrasts in climate between Jamestown and the country areas. Jamestown can be sunny and lightly humid whilst areas like Longwood experience chilly mists and a higher rainfall.