Surf Forecasts:
Cable Bay (Porth Trecastell) surf forecast from 29 Aug 2026:
- Most powerful swell: Wednesday 2 Sep, 7PM (local time) - 8ft (2.4m), 7s period, SW swell with 566 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 2.4m 7s and forecast to arrive on Wednesday (Sep 02) 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 1.2m 5s period and expected on Saturday (Sep 05) at 1AM.
| Wave Type | Time (BST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | - | - |
| Best Surf | - | - |
| Most Powerful | 7PM (Wed 2nd Sep) | 8ft (2.4m) 7s |
Table - best surf conditions forecast for Cable Bay (Porth Trecastell) over the next 16 days.
The Lowdown
Alright, let's look at this as we see it for the next couple of weeks. Cable Bay (Porth Trecastell) is mostly a bust. Most of the time it's going to be poor quality surf thanks to the wind being all wrong or the swell being either too weak or so big it's just messy. We start on Saturday morning, August 29th, with a tiny 3ft SSW swell but a cross-shore wind from the SE at 6 mph – just weak and poor. The water temp is about 64°F, which feels much warmer than normal for this time of year, running about 4°F above the average.
The first week is pretty much a washout. Saturday afternoon cleans up a bit with an offshore wind from the NNE, but the swell drops to just 2ft, so it's small with low energy. Sunday through the following Sunday, September 6th, is a long stretch of building onshore winds with the swell ranging 3ft up to 5ft and even 8ft, but always with strong to fresh onshore breezes making it lumpy and poor. The biggest of that lot is a 7ft SSE swell on Wednesday afternoon, September 2nd, but it's under a 25 mph onshore wind – honestly, that's more for the kite surfers.
We hit a real lull from Monday afternoon, September 7th, through Wednesday morning, September 9th. The surf drops to almost flat – less than 1ft – with no energy, so don't bother dragging the board out. Then Thursday, September 10th, brings a big pulse: a massive 12ft SW groundswell with a period of 8 seconds and huge energy. The wind is light from the SE at 6 mph in the morning, so it would be glassy on top. But there's a big caveat: the forecast says that swell is too big for this break – only for experts, and it'll be serious. After that, it fades back into small, onshore junk from Friday, September 11th onward.
So the only real standout is Thursday morning, September 10th, for the brave and the skilled – that's a huge, clean 12ft SW swell. Everything else in the 16-day window is poor. The gap of days without any solid recommendation stretches from Saturday, August 29th, all the way to that Thursday, September 10th. That's over a week of nothing to ride for the average surfer. The wave energy numbers are mostly two-digit weak or three-digit moderate until that big day which goes to four digits. Stick with it, though – it doesn't stay this quiet forever.
Rusty
Short Range ForecastLight rain (total 6mm), mostly falling on Sat afternoon. Very mild (max 17°C on Sun morning, min 14°C on Mon morning). Winds increasing (light winds from the NW on Sat night, fresh winds from the WNW by Mon morning). | Days 5-7 Weather SummaryLight rain (total 7mm), mostly falling on Wed morning. Very mild (max 17°C on Tue afternoon, min 13°C on Fri morning). Mainly strong winds. | |||||||||||||||||||
Sat 29 | Sunday 30 | Monday 31 | Tuesday 1 | Wednesday 2 | Thursday 3 | Friday 4 | ||||||||||||||
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) | SSW 6 | SSW 8 | SSW 8 | SSW 5 | SW 8 | WNW 6 | NW 5 | SSW 7 | SW 4 | SW 5 | SW 5 | SSW 7 | SW 7 | SW 7 | SW 6 | SW 6 | WSW 7 | W 6 | W 5 | SW 5 |
Wave Graph  | ||||||||||||||||||||
 kJ | 29 | 126 | 92 | 72 | 110 | 143 | 51 | 21 | 29 | 53 | 79 | 444 | 495 | 301 | 171 | 190 | 517 | 366 | 121 | 12 |
Wind (km/h) | ||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | off | on | cross-on | cross-on | cross-on | cross | cross-on | cross-on | on | on | on | cross-on | on | on | on | cross-on | cross-on | cross-on | cross-on | on |
High Tide | 11:00PM4.28m | 11:19AM3.92m | 11:30PM4.30m | 11:49AM3.93m | 00:03AM4.23m | 12:23PM3.87m | 00:40AM4.07m | 1:01PM3.73m | 1:22AM3.82m | 1:47PM3.51m | 2:14AM3.50m | 2:44PM3.26m | 3:24AM3.18m | |||||||
Low Tide | 5:26PM0.21m | 5:52AM0.00m | 6:01PM0.20m | 6:27AM0.05m | 6:37PM0.27m | 7:03AM0.19m | 7:16PM0.42m | 7:43AM0.43m | 7:59PM0.63m | 8:28AM0.72m | 8:50PM0.88m | 9:25AM1.02m | 9:57PM1.11m | |||||||
 |  |  | |  |  |  |  | | |  |  | | |  | | | | | | |
 | — | — | 6:22 | — | — | 6:24 | — | — | 6:26 | — | — | 6:28 | — | — | 6:30 | — | — | 6:31 | — | — |
 | 8:15 | — | — | 8:13 | — | — | 8:09 | — | — | 8:07 | — | — | 8:06 | — | — | 8:02 | — | — | 8:00 | — |
mm | 2 | — | 1 | 2 | 1 | — | — | — | — | 1 | 3 | 3 | — | — | — | — | — | — | — | — |
Temp °C | 16 | 16 | 17 | 16 | 15 | 14 | 16 | 16 | 16 | 17 | 16 | 17 | 17 | 17 | 16 | 17 | 15 | 15 | 17 | 17 |
Feels °C | 15 | 16 | 13 | 11 | 12 | 7 | 13 | 13 | 12 | 13 | 12 | 12 | 11 | 13 | 10 | 10 | 7 | 9 | 14 | 13 |
Swell 1 Height (m) Direction Period (s) | SSW 6 | SSW 8 | — | SW 8 | SW 8 | SW 8 | SW 8 | SSW 7 | — | WNW 4 | — | — | — | SW 15 | SW 14 | SW 14 | — | — | NNW 6 | SW 5 |
| kJ | 29 | 126 | — | 11 | 110 | 64 | 50 | 21 | — | 1 | — | — | — | 9 | 8 | 8 | — | — | 20 | 12 |
Swell 2 Height (m) Direction Period (s) | — | NW 3 | — | — | — | — | — | NNW 5 | — | — | — | — | — | — | — | — | — | — | SW 14 | SW 6 |
| kJ | — | 2 | — | — | — | — | — | 5 | — | — | — | — | — | — | — | — | — | — | 8 | 10 |
Swell 3 Height (m) Direction Period (s) | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | SW 14 |
| kJ | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 8 |
Wind waves Height (m) Direction Period (s) | — | — | SSW 8 | SSW 5 | — | WNW 6 | NW 5 | W 3 | SW 4 | SW 5 | SW 5 | SSW 7 | SW 7 | SW 7 | SW 6 | SW 6 | WSW 7 | W 6 | W 5 | NW 5 |
| kJ | — | — | 92 | 72 | — | 143 | 51 | 5 | 29 | 53 | 79 | 444 | 495 | 301 | 171 | 190 | 517 | 366 | 121 | 74 |
Nearest Offshore or Glassy | ||||||||||||||||||||
Distance (km) | 173 | 44 | 296 | 285 | 44 | 521 | 44 | 44 | 299 | 244 | 256 | 934 | 261 | 284 | 783 | 541 | 541 | 604 | 167 | 44 |
Best forecast wave conditions in Anglesy | ||||||||||||||||||||
Best forecast wave conditions in United Kingdom | ||||||||||||||||||||
Header Global | ||||||||||||||||||||
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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.
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