Windmill Beach dive visibility forecast
False Bay, western shore (Simon's Town)
Probabilistic water-clarity forecast for Windmill Beach (False Bay, western shore (Simon's Town)), a dive site near Cape Town, South Africa. Visibility is modelled from six days of swell and wind history rather than measured, because clarity lags the weather that stirred it.
Windmill Beach, Cape Town — today, Tuesday 18 August 2026: median underwater visibility 5.9 m (80% interval 3.7–9.6 m), 56% chance of diveable conditions in the best daylight hour. Conditions: diveable. Limiting factor: bottom surge. Best window 08:00–18:59.
Windmill Beach, Cape Town — tomorrow, Wednesday 19 August 2026: median underwater visibility 4.8 m (80% interval 2.9–8.0 m), 65% chance of diveable conditions in the best daylight hour. Conditions: diveable. Limiting factor: bottom surge. Best window 08:00–18:59.
Windmill Beach, Cape Town — Thursday 20 August 2026: median underwater visibility 5.2 m (80% interval 3.1–8.7 m), 23% chance of diveable conditions in the best daylight hour. Conditions: touch and go. Limiting factor: bottom surge. Best window 16:00–18:59.
Three-day visibility forecast for Windmill Beach
| Day | Median viz | 80% interval | P(diveable) | Conditions | Limiting factor |
|---|---|---|---|---|---|
| Today, 18 Aug | 5.9 m | 3.7–9.6 m | 56% | Diveable | Bottom surge |
| Tomorrow, 19 Aug | 4.8 m | 2.9–8.0 m | 65% | Diveable | Bottom surge |
| Thursday, 20 Aug | 5.2 m | 3.1–8.7 m | 23% | Touch and go | Bottom surge |
Forecast generated 2026-08-17 23:28 UTC. Updated three times daily.
About Windmill Beach
| Region | False Bay, western shore (Simon's Town) |
|---|---|
| Coordinates | -34.2010, 18.4567 |
| Best realistic visibility | 8 m |
| Modelled working depth | 6 m |
| Forecast horizon | 3 days, hourly |
How to read this forecast
The median is the middle of the modelled distribution: half the ensemble members came out clearer, half murkier. The 80% interval is the spread between the 10th and 90th percentiles — a wide band means the weather models disagree about the swell or wind that will stir the bottom, not that the site is unpredictable in itself.
P(diveable) is the share of ensemble members whose worst safety gate still clears at the best daylight hour. The limiting factor names which gate binds first — entry and exit, bottom surge, current, wind or surface chop. A site can have beautiful water and still be undiveable because the entry is unworkable.
For the full hourly distribution, the fan chart and the uncertainty breakdown, open the live forecast. Method and inputs are set out in the methodology.
theviz forecasts water clarity from swell and wind history. It does not measure it, and it is not navigation or dive-safety advice. Conditions change fast; check locally, dive within your training, and verify marine protected-area boundaries before spearfishing.