
Surf Forecasts:
Big Bay surf forecast from 15 Sep 2026:
- Best quality surf: Friday 18 Sep, 5AM (local time) - 5ft (1.6m), 11s period, SW swell with offshore winds.
- Most powerful swell: Wednesday 16 Sep, 5AM (local time) - 10ft (3.0m), 14s period, WSW swell with 3,316 kJ wave energy.
- Next surfable swell (1★+): Friday 18 Sep, 5AM (local time) - 5ft (1.6m), 11s period with SW swell.
Best Forecast Surf Conditions for Big Bay this week:
The surf forecast for Big Bay over the next 16 days: The first swell (rated 1 star or higher) is forecast to arrive on Friday (Sep 18) at 5AM. The primary swell is predicted to be 1.6m and 11s period with a secondary swell of 1.5m and 6s. The wind is predicted to be offshore as the swell arrives.
The most powerful waves expected at Big Bay in the next 16 days are 3.0m 14s and forecast to arrive on Wednesday (Sep 16) at 5AM. Winds are predicted to be cross-offshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 1.7m 6s period and expected on Wednesday (Sep 16) at 5PM.
| Wave Type | Time (SAST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 5AM (Fri 18th Sep) | 5ft (1.6m) 11s |
| Best Surf | 5AM (Fri 18th Sep) | 5ft (1.6m) 11s |
| Most Powerful | 5AM (Wed 16th Sep) | 10ft (3.0m) 14s |
Table - best surf conditions forecast for Big Bay over the next 16 days.
The Lowdown
Right off the bat, the ocean’s got a pulse, but it’s a messy one. We’re looking at a stretch where the surf is going to be pretty ordinary for a while, with a few serious standouts further down the line. Patience is the name of the game here.
First up, the next few days are pretty grim. Tuesday afternoon is lumpy, cross-onshore junk with a weak 4ft of SW swell. The wave energy is sitting at 1241, which is moderate, but it’s wasted on the chop. Honestly, you’re not missing anything. Wednesday through to Monday the 23rd are all marginal – clean enough at times, but the swell is small and the tide seems to be working against us. It’s that frustrating “could be, but probably won’t be” kind of window. The energy dips into the hundreds (down to 336 on Monday afternoon), and it’s just not worth paddling out for the scraps. There’s a brief window on Friday the 18th afternoon with a fresh offshore, but the swell is only 5ft, it’s short-period stuff at 11 seconds, and the energy is still under a thousand. Not enough push.
Now, here’s where it gets interesting. The first real standout is Thursday the 24th of September. The swell is going to absolutely kick in. We’re talking a solid 13ft of southwest groundswell with a 14-second period. The combined energy is a massive 5810 – that’s strong, and it’s going to make Big Bay (Big-Bay) feel alive. But look, it’s a big one. At 13ft, this is strictly for the experts. The morning sees a 25 km/h cross-offshore wind, which will keep it somewhat clean, but this is a serious, powerful slab. The afternoon drops to 12ft with the energy still over 4864. This is a “stand on the bluffs and watch” day unless you’ve got serious balls.
Friday the 25th is the pick of the bunch for the experienced crew. The swell backs off to a still-chunky 8ft in the morning, with the same long-period SW groundswell. The wind drops to a slight air, making for clean, glassy conditions. The energy is a healthy 2174. This is the one. It’s got size, it’s got power, and it’s clean. Definitely a standout for the experts.
Then it goes a bit weird. Saturday the 26th throws a curveball – the swell jumps back up to 13ft in the afternoon with a 15-second period and energy at 6926, but the wind turns cross-onshore. It’s going to be a big, messy, bumpy beast. Not the one. Same for Sunday – still solid 10ft but with a cross-shore wind. It’s powerful but lumpy.
But then, just when you think it’s over, Monday the 28th morning delivers another gem. The swell has dropped to a still-very-respectable 8ft, the period is 13 seconds, and the wind is a clean 15 km/h cross-offshore. The energy is 1671, and the conditions are described as excellent for experienced surfers. This is another big, clean day at Big Bay. The afternoon backs off a bit.
Finally, we get a glassy morning on Tuesday the 29th. The swell is a more manageable 5ft, the period is 11 seconds, and we’ve got glassy conditions with a slight air. It’s a much smaller, user-friendly day, and the energy is only 613. A dawn patrol for the longboarders, maybe.
After that, it fades off into mush and onshore junk for the 30th, so we’re done by then. The water temp is sitting at 55°F, which is 5°F colder than normal for this time of year – that’s a big deal. You’re going to want the 5/4 and booties.
So, looking at the whole window, Friday the 25th and Monday the 28th stand out as the best on offer – both with serious size, long-period SW swell, and decent winds. But these are for experienced surfers only. The long-period swell at a beach break can make it close out, so you need to pick your bank. The 24th is for experts only – that’s a life-changing kind of size. Everything else is either too small, too messy, or too gnarly.
That’s the story. Stay safe out there.
Rusty
Short Range ForecastModerate rain (total 19mm), heaviest on Tue night. Very mild (max 17°C on Thu afternoon, min 12°C on Tue night). Winds decreasing (strong winds from the SSE on Wed afternoon, light winds from the ESE by Fri morning). | Days 5-7 Weather SummaryMostly dry. Warm (max 23°C on Mon morning, min 13°C on Fri night). Wind will be generally light. | |||||||||||||||||||
Tue 15 | Wednesday 16 | Thursday 17 | Friday 18 | Saturday 19 | Sunday 20 | Monday 21 | ||||||||||||||
PM | Night | AM | PM | Night | AM | PM | Night | AM | PM | Night | AM | PM | Night | AM | PM | Night | AM | PM | Night | |
Swell Height Map | ||||||||||||||||||||
Wave Height (m) Direction Period (s) | SW 16 | SW 14 | SW 13 | WSW 13 | SW 13 | SW 12 | SW 12 | SW 11 | SW 11 | SW 11 | SW 12 | SW 12 | SW 12 | SW 14 | SW 14 | WSW 13 | WSW 12 | WSW 12 | WSW 12 | WSW 11 |
Wave Graph | ||||||||||||||||||||
813 | 3236 | 2787 | 1156 | 1352 | 1031 | 945 | 673 | 640 | 600 | 736 | 522 | 435 | 1215 | 1367 | 1014 | 647 | 436 | 336 | 270 | |
Wind (km/h) | ||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross-on | cross-off | cross-off | cross-off | cross-off | cross-off | cross-off | cross-off | cross-off | off | off | cross-off | cross-off | cross-off | cross-off | cross-off | off | off | cross | cross-off |
High Tide | 5:29PM1.40m | 5:49AM1.24m | 6:00PM1.27m | 6:24AM1.13m | 6:36PM1.13m | 7:10AM1.01m | 7:30PM1.00m | 8:48AM0.92m | 9:37PM0.93m | 11:20AM0.96m | 11:39PM0.99m | 12:26PM1.08m | 00:34AM1.10m | |||||||
Low Tide | 11:44PM0.28m | 11:48AM0.38m | 00:15AM0.41m | 12:20PM0.51m | 00:53AM0.53m | 1:03PM0.63m | 2:02AM0.64m | 2:56PM0.73m | 4:47AM0.65m | 5:47PM0.67m | 6:11AM0.55m | 6:42PM0.56m | ||||||||
— | — | 6:43 | — | — | 6:43 | — | — | 6:41 | — | — | 6:39 | — | — | 6:39 | — | — | 6:37 | — | — | |
6:37 | — | — | 6:37 | — | — | 6:37 | — | — | 6:38 | — | — | 6:39 | — | — | 6:39 | — | — | 6:40 | — | |
mm | — | 19 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
Temp °C | 16 | 14 | 15 | 16 | 14 | 15 | 17 | 14 | 16 | 19 | 15 | 17 | 20 | 17 | 20 | 20 | 17 | 23 | 25 | 23 |
Feels °C | 9 | 9 | 7 | 7 | 7 | 8 | 9 | 6 | 12 | 13 | 10 | 14 | 17 | 14 | 17 | 17 | 15 | 23 | 24 | 25 |
Swell 1 Height (m) Direction Period (s) | SW 16 | SW 14 | SW 13 | WSW 13 | SW 13 | SW 12 | SW 12 | SW 11 | SW 11 | SW 11 | SW 12 | SW 12 | SW 12 | SW 14 | SW 14 | WSW 13 | WSW 12 | WSW 12 | WSW 12 | WSW 11 |
813 | 3236 | 2787 | 1156 | 1352 | 1031 | 945 | 673 | 640 | 600 | 736 | 522 | 435 | 1215 | 1367 | 1014 | 647 | 436 | 336 | 270 | |
Swell 2 Height (m) Direction Period (s) | — | WNW 8 | SW 14 | SW 13 | W 12 | W 12 | — | — | W 20 | SW 18 | SW 16 | SSE 6 | SW 15 | — | — | — | SSE 6 | S 6 | — | SSE 6 |
— | 166 | 534 | 628 | 383 | 139 | — | — | 7 | 12 | 41 | 88 | 136 | — | — | — | 82 | 34 | — | 10 | |
Swell 3 Height (m) Direction Period (s) | — | — | — | — | — | — | — | — | — | — | — | SW 15 | SSW 18 | — | — | — | — | — | — | SW 14 |
— | — | — | — | — | — | — | — | — | — | — | 174 | 31 | — | — | — | — | — | — | 30 | |
Wind waves Height (m) Direction Period (s) | NW 7 | — | — | S 6 | SSE 7 | SSE 7 | S 6 | SSE 6 | SSE 7 | SSE 7 | SSE 6 | SE 7 | SSE 6 | SSE 6 | S 7 | SSE 6 | SE 7 | — | S 6 | — |
428 | — | — | 200 | 261 | 268 | 361 | 195 | 77 | 268 | 115 | 214 | 245 | 115 | 126 | 144 | 178 | — | 24 | — | |
Nearest Offshore or Glassy | ||||||||||||||||||||
Distance (km) | 192 | 456 | 340 | 163 | 56 | 166 | 400 | 0 | 0 | 1408 | 0 | 0 | 340 | 0 | 0 | 0 | 0 | 0 | 14 | 0 |
Best forecast wave conditions in Cape Town | ||||||||||||||||||||
Best forecast wave conditions in South Africa | ||||||||||||||||||||
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Information about the Big Bay Surf forecast
The above surf forecast table for Big Bay provides essential information for determining whether the surfing conditions will be good over the next 16 days. A general guide to surfing at Big Bay can be found by selecting the local surf guide option on the grey menu. Our Big Bay surf forecast is unique since it includes wave energy (power) that defines the real feel of the surf rather than just the height or the period. If you surf the same spot (Big Bay) regularly then make a mental note of the wave energy from the surf forecast table each time you go. Very soon you may start to choose your surf days based on the wave energy alone combined with our forecast of favourable offshore wind conditions. Our star ratings will help here and of course you will also find the usual wave height and period predictions on our surf forecasts as well as a full break down of the swell components under our advanced users option (to reveal that, click the little Einstein character under the tide times).
Further information to help with frequently asked questions about our surf forecast for Big Bay may be found under the help tab on the top menu and also by moving your mouse over the question marks on the surf forecast table itself. Please always bear in mind that the forecast is for near-shore open water and local factors at each surf break influence the actual breaking wave height, such as the beach / reef profile, water depths offshore and shelter.
Big Bay is 8 km (5 miles) from the very large city of Robben Island. If you plan a holiday in Cape Town, look for hotels and other accommodation in Robben Island. Robben Island has rooms for a wide range of budgets as well as cheap car hire and transport links.










