Reading the weather in the South Atlantic

Wavy talks through the kind of weather we encounter on our epic voyage across the South Atlantic to St Helena island

Wavy Immelman
by Wavy Immelman ·

The South Atlantic Oceans weather is, like all weather, quite fickle. However there are some very dominant systems which we use to do our routing plans.

Weather in the South Atlantic

Firstly there is the South Atlantic High-Pressure system, or the St Helena High. This high pressure is driven by the ITCZ inter-tropical convergence zone or doldrums, low pressure and the temperate low pressures that form in the south. High-pressure systems turn in a counterclockwise direction in the southern hemisphere, while low pressures turn in a clockwise direction. This is a major influence on our route planning.

Secondly, there are the low-pressure systems moving from west to east in the temperate zone, further south in the Atlantic.

Leg 1: Cape Town to St Helena Island

Leaving Cape Town we will wait for the high pressure to start blowing from the southeast, usually quite strong, giving us a good early push north. Instead of aiming straight at St Helena Island, we would tend to follow the curve of the high pressure around the 1018 bar contour line. This tends to take us north early, along the African coast, then deeper into the Atlantic around southern Namibia. Due to this, a short stop in Lüderitz in southern Namibia is a fun and interesting little stop en route.

From there it is a straight shot to St Helena Island, with some lovely downwind sailing and a following sea. Give or take 10 days of sailing in ideal conditions and warm seas.

At St Helena it is generally an easterly wind driven by high-pressure, again being the predominant system in our route planning.. After a lovely stop on one of the friendliest islands in the world, We head southwest. Yes that is away from Cape Town our final destination, however, it is once again following the curve of the St Helena High Pressure.

Leg 2: St Helena Island to Cape Town

As we head south west things get a little more fickle, as the influence of the low pressures comes into play. Moving from west to east they are the next target for a down wind sail toward Cape Town. Depending on the seasons we would tend to change our south westerly course for an easterly heading for south of Cape Town around 35 to 36 degrees south, The low pressures can however be quite strong and the sailing can get a little more challenging. Having said that, the fact that they are moving fast across the Atlantic, the foul weather never really lasts for more than 24 hours, leaving behind some calmer weather.

The final leg in, is aiming south of Cape Town, to once again pick up the south easterly winds which we started with. This allows us a spectacular sail up the Cape of Good Hope and into Cape Town.

Planning your Ocean Crossing

In summary, like all ocean crossings, the weather is the most important influence on any route plan, and we literally use it to our full advantage by sailing around the South Atlantic high pressure. It does mean that although the route is longer on the return leg, it is still predominantly a downwind leg. With the odd bit of fickle weather caused by the passing low pressures. A fun and sometimes challenging sail which takes us to unique and interesting destinations which leaves one feeling very proud of the achievement and full of good memories.

If you fancy experiencing the weather of the South Atlantic for yourself, check out availability on our website : St Helena trips