Winds and Weather:

A central area of high pressure dominates the South Atlantic, and both the wind and current systems (see diagrams) circulate in an anti-clockwise direction. The southeast trade winds flow around this high which is generally centered between 20deg. to 28deg. S, and blows with consistency from S.S.E. on the African side to almost east close to the North Brazilian coastline.

In summer the southeast trades are normally encountered a few days sail NW of Cape Town, and are often heralded by a day of light fluffy clouds. Line squalls followed by stronger winds and sometimes heavy rain, are often encountered in mid ocean, and towards the North Eastern Brazilian coastline.

If headed to the Caribbean the Doldrum belt is narrow, with torrential rain, and will be encountered close to the mouth of the Amazon River.

Fog, or sea fog, are very common in the Cape Town area and northwards, in the autumn months with very limited visibility.

Further North, towards the deserts of Namibia, fog often occurs in any season, the worst conditions develop at night, when the overlaying air is cooled, as it encounters the cold Benguela Current.

Inshore, in the summer months, the fog usually clears by noon.

Sea and swell:

Moderate to heavy swell from between SW and NW, depending on wind strength and direction occurs off the Cape area. Very rough and confused seas are common in winter, occurring anything up to 25deg. S, right across the South Atlantic.

Heavy seas are rare north of 25deg. S, but can develop during violent squalls. North of latitude 10deg. S, the sea is slight in summer between SE and SW.

Changes in direction and strength of the SE trades, can cause landing and anchorage problems at the South Atlantic islands.

About 3 days in any summer month "rollers" occur at St Helena, Ascension and Fernando de Noronha islands making landing almost impossible.

For full details with photos, charts, diagrams, etc., see "Cape to Caribbean Cruising Notes" by Tony Herrick http://www.cruiser.co.za/tony.asp