Surf Forecasts:
Cable Bay (Porth Trecastell) surf forecast from 17 Aug 2026:
- Most powerful swell: Wednesday 19 Aug, 7PM (local time) - 4.5ft (1.4m), 6s period, SW swell with 133 kJ wave energy.
Best Forecast Surf Conditions for Cable Bay (Porth Trecastell) this week:
The most powerful waves expected at Cable Bay (Porth Trecastell) in the next 16 days are 1.4m 6s and forecast to arrive on Wednesday (Aug 19) at 7PM. Winds are predicted to be onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 1.3m 5s period and expected on Thursday (Aug 20) at 1PM.
| Wave Type | Time (BST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | - | - |
| Best Surf | - | - |
| Most Powerful | 7PM (Wed 19th Aug) | 4.5ft (1.4m) 6s |
Table - best surf conditions forecast for Cable Bay (Porth Trecastell) over the next 16 days.
The Lowdown
Alright folks, Rusty here. Let's have a look at what Cable Bay (Porth Trecastrell) has got cooking for us over the next couple of weeks. I'll be straight with you, it's a bit of a mixed bag, and we've got a proper dry spell to get through before anything really happens.
First up, we've got a long, quiet period. From Monday the 17th right through to the morning of Tuesday the 26th of August, it's pretty much a flat spell. We're talking tiny waves, poor conditions, and energy readings in the single digits or teens – combined wave energy is as low as 7 (for example, on the 25th). There's a slight breeze at times, but honestly, it's not worth paddling out for. You'd be fighting for scraps. The water temp is about average for this time of year, so don't expect any surprises there.
Then things finally start to wake up. On the afternoon of Wednesday the 26th of August, we see a pulse of swell arrive, pushing to 8ft from the SSW with a period of 7 seconds. The energy jumps to 708, but the wind is a moderate cross-shore breeze, so it'll have a bit of chop on it. The guidance calls it marginal, so don't get your hopes up too high.
But hold onto your board, because Thursday the 27th of August is where it gets interesting. The swell cranks up properly: 12ft from the SW with an 8-second period, and the combined energy hits a huge 1550. The wind is a moderate cross-shore again. Now, an 12ft wave is big – this is for experienced surfers only. Beginners, stay on the beach. This break is exposed to the SW, which is in the ballpark of the optimum direction, so it should be wrapping in nicely. The wind is cross-shore, which isn't terrible, but it's not the cleanest. If you're an expert, this is one of the few windows where it's actually worth checking. It's a fairly consistent spot when it gets swell, so this is the standout of the whole outlook.
After that blast, it drops off quickly again. Friday the 28th of August sees the swell drop to 2ft, and the rest of the forecast period is a mess of small, marginal, or clean but tiny waves with energy barely cracking 100. There's a bit of a spike on Sunday the 30th of August, with a 7ft swell from the SW and clean offshore winds from the NNE, but the guidance calls it marginal, likely due to tide. Still, with a 7-second period and moderate wave energy of 381, it might offer a few runners for those who are keen.
Overall, the whole 16-day outlook is a tale of two halves: a whole lot of nothing, then one proper big day for the brave crew, followed by another lull. The main event is undoubtedly Thursday the 27th – that's your best shot.
Stay salty,
Rusty
Short Range ForecastLight rain (total 8mm), mostly falling on Mon night. Very mild (max 18°C on Tue night, min 14°C on Tue night). Winds increasing (light winds from the W on Sun night, fresh winds from the SSW by Wed afternoon). | Days 4-6 Weather SummaryLight rain (total 4mm), mostly falling on Wed night. Very mild (max 16°C on Thu morning, min 13°C on Thu night). Winds decreasing (fresh winds from the N on Thu morning, light winds from the NNE by Fri night). | ||||||||||||||||||||
Monday 17 | Tuesday 18 | Wednesday 19 | Thursday 20 | Friday 21 | Saturday 22 | Sunday 23 | |||||||||||||||
AM | 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 5 | SW 5 | SW 5 | SW 5 | SW 6 | W 4 | WSW 5 | SW 5 | SW 6 | SW 6 | SW 6 | SW 14 | NW 4 | SW 13 | SW 13 | SW 15 | SW 15 | SW 15 | NW 4 | WNW 4 | SW 14 |
Wave Graph | |||||||||||||||||||||
6 | 4 | 31 | 22 | 16 | 18 | 92 | 93 | 105 | 18 | 10 | 8 | 7 | 7 | 7 | 8 | 8 | 8 | 8 | 7 | 8 | |
Wind (km/h) | |||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross-on | cross-on | on | cross-on | on | cross-on | on | on | cross-on | cross-off | cross-off | cross-off | cross | cross-off | cross-off | cross-off | cross-off | off | cross-on | cross-on | on |
High Tide | 1:04PM3.73m | 1:21AM3.95m | 1:44PM3.51m | 2:05AM3.58m | 2:29PM3.25m | 2:56AM3.21m | 3:26PM3.00m | 4:05AM2.90m | 4:46PM2.83m | 5:38AM2.76m | 6:19PM2.84m | 7:04AM2.82m | 7:32PM3.02m | ||||||||
Low Tide | 7:34AM0.15m | 7:45PM0.46m | 8:13AM0.53m | 8:25PM0.77m | 8:54AM0.92m | 9:10PM1.10m | 9:40AM1.27m | 10:08PM1.38m | 10:45AM1.54m | 11:34PM1.55m | 12:20PM1.61m | 1:12AM1.48m | 1:41PM1.46m | 2:17AM1.25m | |||||||
6:00 | — | — | 6:01 | — | — | 6:03 | — | — | 6:05 | — | — | 6:07 | — | — | 6:09 | — | — | 6:11 | — | — | |
— | 8:42 | — | — | 8:39 | — | — | 8:37 | — | — | 8:36 | — | — | 8:32 | — | — | 8:30 | — | — | 8:29 | — | |
mm | — | — | 5 | — | — | — | — | 2 | 4 | — | — | — | — | — | — | — | — | — | — | — | — |
Temp °C | 16 | 16 | 17 | 16 | 17 | 18 | 16 | 16 | 15 | 16 | 16 | 14 | 15 | 16 | 14 | 16 | 16 | 14 | 14 | 16 | 16 |
Feels °C | 16 | 15 | 16 | 13 | 14 | 14 | 10 | 10 | 12 | 10 | 11 | 11 | 12 | 11 | 10 | 11 | 11 | 12 | 11 | 13 | 14 |
Swell 1 Height (m) Direction Period (s) | SW 5 | SW 5 | — | SW 5 | NW 4 | — | SW 16 | S 15 | SW 16 | SW 6 | SW 6 | SW 6 | NW 4 | SW 5 | SW 13 | SW 15 | SW 15 | SW 15 | SW 14 | N 4 | — |
6 | 4 | — | 22 | 8 | — | 10 | 5 | 10 | 18 | 10 | 1 | 7 | 1 | 7 | 8 | 8 | 8 | 8 | 1 | — | |
Swell 2 Height (m) Direction Period (s) | — | NW 3 | — | — | — | — | — | — | — | SW 15 | SW 14 | SW 14 | SW 5 | SW 13 | — | — | — | SW 12 | — | SW 14 | SW 14 |
— | 2 | — | — | — | — | — | — | — | 8 | 8 | 8 | 1 | 7 | — | — | — | 6 | — | 7 | 8 | |
Swell 3 Height (m) Direction Period (s) | — | — | — | — | — | — | — | — | — | — | — | — | SW 14 | — | — | — | — | — | — | — | — |
— | — | — | — | — | — | — | — | — | — | — | — | 7 | — | — | — | — | — | — | — | — | |
Wind waves Height (m) Direction Period (s) | NW 3 | WNW 3 | SW 5 | NW 4 | SW 6 | W 4 | WSW 5 | SW 5 | SW 6 | NNW 4 | N 5 | NNW 5 | NE 3 | N 3 | N 4 | NNW 5 | NNW 4 | NNW 4 | NW 4 | WNW 4 | — |
3 | 2 | 31 | 18 | 16 | 18 | 92 | 93 | 105 | 37 | 62 | 43 | 2 | 3 | 11 | 29 | 10 | 5 | 8 | 5 | — | |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 258 | 297 | 576 | 44 | 506 | 261 | 256 | 256 | 96 | 173 | 338 | 172 | 172 | 284 | 272 | 260 | 211 | 211 | 283 | 290 | 158 |
Best forecast wave conditions in Anglesy | |||||||||||||||||||||
Best forecast wave conditions in United Kingdom | |||||||||||||||||||||
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Information about the Cable Bay (Porth Trecastell) Surf forecast
The above surf forecast table for Cable Bay (Porth Trecastell) provides essential information for determining whether the surfing conditions will be good over the next 16 days. A general guide to surfing at Cable Bay (Porth Trecastell) can be found by selecting the local surf guide option on the grey menu. Our Cable Bay (Porth Trecastell) 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 (Cable Bay (Porth Trecastell)) 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 Cable Bay (Porth Trecastell) 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.
Are you planning a holiday in Anglesy? If you are looking for accommodation near Cable Bay, camping, hotels and holiday cottages in Anglesy, consider staying in Anglesey which is 4 km (2 miles) away. Other places in and around Anglesy where you can find information about places to rent, and car hire include Holyhead which is 14 km (9 miles) away, Bangor, Porthmadog and Llandudno.











