St Helena, Ascension and Tristan da Cunha - When and where to visit
The climate on Ascension may be sub-tropical, but it is much cooler and drier than that would suggest, with temperatures kept relatively moderate by the persistent southeast trade winds. At sea level, they average around 79°F (26°C) year-round, peaking in the mid 80s (30s) during the early part of the year, when humidity can be quite high. On Green Mountain, it’s usually about 10–15°F (4–7°C) cooler. Showers occur throughout the year, with a tendency to being heavier around February and March, but Green Mountain is considerably wetter than the lower-lying areas.
The main tourist season on St Helena is from November to March, when it is summer in the southern hemisphere and the days are predominantly sunny and hot. You can expect some rainfall, especially out of Jamestown in March, but rarely does it last long at this time of year. Between April and October there are fewer tourists, but it is noticeably cooler than in the summer months, and generally wetter too.
One of St Helena’s biggest draws is the appearance of whale sharks around the island. They are usually present between November and May, but visitors in January will have the greatest chance of seeing and perhaps swimming with these truly gentle giants. The other big marine attraction, humpback whales, arrive during the winter months, between July and December, with calves being present from August. Pods of dolphins, especially the pan-tropical spotted species, are regularly seen off the northwest coast throughout the year. For birders, the must-see is the wirebird, St Helena’s only surviving endemic bird, which is surprisingly easy to spot year round. Even for the least-interested visitor, the knowledge that you are in the only place in the world where you can see this little plover is pretty humbling.
St Helena’s unique flora is a botanist’s dream: some 45 endemic plants, many on the brink of extinction. Trees on the peaks flower in succession, so there’s no best time to see them, but if you’d like to spot species like babies’ toes and ice plant in flower, you’ll need to be here around November to January.
Military history and its related sites abound, from the garrisons established by the East India Company through the whole story of Napoleon’s exile and on to the Boer War. While there’s no ‘best’ time to visit such places, there will be considerable extra interest in the Napoleonic sites between October 2015 and May 2021, which mark the bicentenary of the former emperor’s time on the island.
Dramatic seascapes, scenic grandeur and postbox walks attract and challenge hikers. Walking in the summer months, with a fierce overhead sun and little shade, can be difficult, but there’s usually a breeze outside Jamestown, and the rewards are significant. It’s often more pleasant later in the year, although rainfall tends to be higher between July and September.
Clear water with good visibility, interesting marine life – including some easily spotted endemic fish – and numerous wrecks make diving a very attractive option on St Helena. Water temperatures are warmest between about October and April, but diving is possible year-round. That said, there are occasions when the rollers are up and the sea too rough; typically this is in the early part of the year, and can last about a week.