Wind speed
Go0–8 ktsCalm to light — glass-off surface, excellent visibility, easy entries.
Marginal8–15 ktsChop building — manageable at sheltered spots, plan for morning before sea breeze peaks.
No-go>15 ktsStrong chop — reduced visibility, surge at rock entries, physically tiring in water.
Cape Doctor (SE wind): Good for Atlantic side — clears the water and blows offshore. But it funnels into False Bay, making Simon's Town choppy. When it blows, go to Oudekraal or Sea Point.
Swell height
Go<1 mFlat — ideal rock entries, clean water column, easy to stay in position.
Marginal1–2 mRock entries need timing — wait for the lull, surge can pin you against rocks.
No-go>2 mDangerous entries at most spots — go to a sheltered lagoon like Langebaan instead.
Sheltered spots: Langebaan Lagoon, Knysna Lagoon, and Mossel Bay are largely protected from open ocean swell. At these spots you only need to worry about wind chop, not swell height.
Wave period (seconds)
Choppy<8 sWind swell — short, steep, messy. Murky water even if height seems small.
OK8–12 sMixed swell — manageable with small height. Gaps between sets are usable.
Smooth>12 sLong-period groundswell — even at 1.5m it's clean between sets. More predictable.
Visibility
Excellent8–20+ mAfter SE wind or settled conditions — typical for False Bay and KZN.
OK3–8 mTypical Western Cape — enough to see fish and features but not crystal clear.
Poor<3 mAfter NW wind, heavy rain, or surge stirring sand. Not worth diving.
Langebaan tip: Sandy bottom means visibility drops fast when wind stirs the lagoon. Best visibility is early morning before sea breeze builds, ideally after a calm night.
Wind direction quick guide
GoSE windAtlantic coast spots (Oudekraal, Sea Point) — offshore, clears water.
No-goNW/W windAtlantic coast — onshore swell builder. Switch to False Bay.
GoNW/N windFalse Bay (Simon's Town, Miller's Point) — offshore, glass-off conditions.
GoAny <12 ktsLangebaan Lagoon — sheltered from swell, only wind chop matters.
GoN/NE windKZN coast and Hermanus — offshore, calm surface, best visibility.
Water temperature by region
West Coast12–16°C year-round — cold Benguela upwelling. 5mm full suit, boots, hood.
False Bay14–18°C — slightly warmer. 5mm suit, boots recommended.
Garden Route16–22°C — transitional. 3–5mm depending on season.
KwaZulu-Natal22–28°C — warm Agulhas current. 3mm shorty or skin suit.