What wetsuit do you need in Tongaat?
If you buy one suit for swimming in Tongaat, buy a nothing — it covers 8 of the months people actually swim here. The sea runs from 20.7°C in August to 25.9°C in February.
Swimming and surfing are not the same answer
Nearly every wetsuit chart online is a surfing chart, because surf brands publish them — and surfing is close to the worst case. A session runs one to three hours, most of it sitting still on the board with your torso and head out of the water and in the wind. Little heat is being made and plenty is being lost.
Swimming is the opposite. A steady front crawl produces several hundred watts continuously, and you are horizontal and fully immersed rather than sitting in a breeze. Open-water swimmers routinely go a full step thinner than a surf chart says. Applying one number to both is where the usual charts go wrong, so both are given below.
Month by month
| Month | Sea | Swimming | Surfing | Also |
|---|---|---|---|---|
| January | 25.2°C | nothing | boardshorts | — |
| February | 25.9°C | nothing | boardshorts | — |
| March | 25.5°C | nothing | boardshorts | — |
| April | 24.3°C | nothing | boardshorts | — |
| May | 23.6°C | nothing | boardshorts, or a rash vest against the board | — |
| June | 22.1°C | nothing | boardshorts, or a rash vest against the board | — |
| July | 21.3°C | nothing, or a rash vest | boardshorts, or a rash vest against the board | — |
| August | 20.7°C | nothing, or a rash vest | shorty or a 2 mm top | — |
| September | 20.9°C | nothing, or a rash vest | shorty or a 2 mm top | — |
| October | 21.6°C | nothing, or a rash vest | boardshorts, or a rash vest against the board | — |
| November | 22.6°C | nothing | boardshorts, or a rash vest against the board | — |
| December | 23.6°C | nothing | boardshorts, or a rash vest against the board | — |
What thickness does not fix
A thicker suit buys time, not immunity, and it does nothing about the two things that actually catch people out: the cold shock in the first minute, and how cold you get after you are out. Neoprene that is soaked and in the wind cools you faster than standing there in dry clothes would. Get changed straight away rather than standing about in it.
Fit matters more than millimetres. A wetsuit works by holding a thin layer of water still against your skin; a loose one keeps flushing that layer and replacing it with cold sea, and a baggy 5/4 will lose to a well-fitted 3/2.
See also the sea temperature and swimming season in Tongaat, including what the air does when you get out.
Other coastal cities in South Africa
Where these numbers come from
Sea temperatures are the NOAA OISST satellite climatology for the water off Tongaat; the thicknesses are retail and open-water convention rather than physics. Individual cold tolerance varies far more than the bands do — people differ by a couple of degrees in both directions, and acclimatisation over a season moves it further. Treat this as a starting point, not a prescription. Full method.