Surf Forecasts:
Cable Bay (Porth Trecastell) surf forecast from 19 Aug 2026:
- Best quality surf: Thursday 20 Aug, 7AM (local time) - 2ft (0.6m), 6s period, SW swell with cross-offshore winds.
- Most powerful swell: Thursday 20 Aug, 4AM (local time) - 2.5ft (0.8m), 6s period, SW swell with 46 kJ wave energy.
- Next surfable swell (1★+): Thursday 20 Aug, 7AM (local time) - 2ft (0.6m), 6s period with SW swell.
Best Forecast Surf Conditions for Cable Bay (Porth Trecastell) this week:
The surf forecast for Cable Bay (Porth Trecastell) over the next 16 days: The first swell (rated 1 star or higher) is forecast to arrive on Thursday (Aug 20) at 7AM. The primary swell is predicted to be 0.6m and 6s period with a secondary swell of 0.1m and 15s. Another secondary swell of 0.7m and 4s is also forecast. The wind is predicted to be cross-offshore as the swell arrives.
The most powerful waves expected at Cable Bay (Porth Trecastell) in the next 16 days are 0.8m 6s and forecast to arrive on Thursday (Aug 20) at 4AM. Winds are predicted to be cross-shore 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+) | 7AM (Thu 20th Aug) | 2ft (0.6m) 6s |
| Best Surf | 7AM (Thu 20th Aug) | 2ft (0.6m) 6s |
| Most Powerful | 4AM (Thu 20th Aug) | 2.5ft (0.8m) 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’s cooking at Cable Bay (Porth Trecastell) over the next couple of weeks.
Honestly, I’ve gotta be straight with you – the first week and a half is a tough slog. The water is sitting at 65°, which is a proper 5° warmer than usual for this time of year, so that’s a weird one. But that’s about the only excitement for a while. From the 19th of August right through to the 26th, we’re looking at tiny, weak swells, often with poor period or onshore wind. The combined energy is just a measly 8 to 34 (weak), so you’re basically staring at a flat lake. A few mornings have some clean, cross-off wind, but with waves barely reaching 0.3 ft, there’s nothing to ride.
Now, hold on to your board, because things take a dramatic turn. The standout window is the 27th of August. Thursday morning sees a massive pulse of swell, 10 ft from the SW, but with a short period of 7 seconds. The combined energy hits 731 (strong), so there’s plenty of power. But here’s the catch – that morning, it’s forecasted to be too big for this spot. The wind is light and cross-onshore, but the swell size is just too much for Cable Bay. That afternoon, however, is the real deal. The swell drops to 8 ft from the SW, still a solid 7-second period, and the energy is still a strong 612. The wind swings to a light cross-off from the NNW. That’s glassy, clean conditions. The waves will be big, powerful, and a bit tricky – definitely for experienced surfers only. The long gaps between sets from that period will make paddling out easier, though. This is the one session to target.
After that, it’s right back to the doldrums. From the 28th of August through to the 3rd of September, the swell drops back to under 3 ft, with weak energy (values between 19 and 54) and mostly onshore or cross-onshore wind. The 3rd of September sees a stronger wind, 19 mph from the S, with a lumpy, choppy sea. Not a pretty picture.
So, to sum it up: don’t bother for the first week, but mark your calendar for the afternoon of the 27th of August at Cable Bay. It’s a big, clean swell for the experienced crew.
Rusty.
Short Range ForecastModerate rain (total 14mm), heaviest on Thu morning. Very mild (max 17°C on Wed afternoon, min 12°C on Thu night). Wind will be generally light. | Days 5-7 Weather SummaryMostly dry. Warm (max 22°C on Mon afternoon, min 13°C on Sat night). Wind will be generally light. | |||||||||||||||||||
Wed 19 | Thursday 20 | Friday 21 | Saturday 22 | Sunday 23 | Monday 24 | Tuesday 25 | ||||||||||||||
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 4 | SW 6 | SW 6 | SW 6 | SW 14 | SW 14 | SW 13 | SW 13 | SW 15 | SW 15 | SW 15 | SW 14 | SW 14 | SW 14 | SW 14 | SW 13 | SW 13 | SW 13 | SW 13 | SW 13 |
Wave Graph  | ||||||||||||||||||||
 kJ | 26 | 44 | 16 | 10 | 8 | 7 | 7 | 7 | 8 | 8 | 8 | 8 | 7 | 8 | 8 | 7 | 7 | 7 | 7 | 7 |
Wind (km/h) | ||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | on | cross-on | cross-off | cross-off | cross-off | cross-off | cross-off | cross-off | cross-off | cross | cross-off | cross-off | cross-off | off | off | off | cross-off | cross-off | cross-off | cross-off |
High Tide | 2:56AM3.21m | 3:26PM3.00m | 4:05AM2.90m | 4:46PM2.83m | 5:38AM2.76m | 6:19PM2.84m | 7:04AM2.82m | 7:32PM3.02m | 8:05AM2.99m | 8:24PM3.28m | 8:49AM3.20m | 9:03PM3.55m | ||||||||
Low Tide | 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 | 2:33PM1.20m | 3:02AM0.96m | 3:12PM0.93m | 3:39AM0.68m | |||||||
 |  |  | |  |  |  |  | | | | | | | | | | | | | |
 | — | — | 6:05 | — | — | 6:07 | — | — | 6:09 | — | — | 6:11 | — | — | 6:11 | — | — | 6:13 | — | — |
 | 8:37 | — | — | 8:36 | — | — | 8:32 | — | — | 8:30 | — | — | 8:29 | — | — | 8:27 | — | — | 8:23 | — |
mm | 2 | 6 | 5 | 1 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 13 |
Temp °C | 17 | 16 | 16 | 15 | 14 | 16 | 17 | 14 | 14 | 15 | 15 | 16 | 17 | 17 | 21 | 22 | 19 | 22 | 23 | 18 |
Feels °C | 12 | 15 | 13 | 10 | 10 | 13 | 13 | 11 | 11 | 13 | 13 | 14 | 14 | 14 | 19 | 20 | 13 | 17 | 19 | 15 |
Swell 1 Height (m) Direction Period (s) | WNW 4 | SW 6 | SW 6 | SW 6 | SSW 6 | W 4 | W 3 | SW 13 | SW 15 | NNW 5 | N 5 | N 4 | N 4 | SW 14 | SW 14 | SW 13 | SW 13 | SSE 4 | SSE 4 | NE 6 |
| kJ | 1 | 44 | 16 | 10 | 4 | 3 | 1 | 7 | 8 | 19 | 11 | 6 | 3 | 8 | 8 | 7 | 7 | 4 | 3 | 11 |
Swell 2 Height (m) Direction Period (s) | S 15 | SW 16 | SW 15 | SW 14 | SW 14 | SW 6 | SW 6 | — | — | SW 15 | SW 15 | SW 14 | SW 14 | — | W 9 | SW 9 | SW 8 | SW 13 | SW 13 | SW 8 |
| kJ | 5 | 10 | 8 | 8 | 8 | 1 | 1 | — | — | 8 | 8 | 8 | 7 | — | 2 | 3 | 3 | 7 | 7 | 2 |
Swell 3 Height (m) Direction Period (s) | — | — | — | — | — | SW 14 | SW 13 | — | — | — | S 12 | — | — | — | — | — | SW 8 | SW 8 | SW 8 | SW 13 |
| kJ | — | — | — | — | — | 7 | 7 | — | — | — | 3 | — | — | — | — | — | 3 | 3 | 3 | 7 |
Wind waves Height (m) Direction Period (s) | SW 4 | WNW 4 | NNW 5 | N 5 | NNW 5 | NNW 5 | N 4 | NNW 5 | NNW 5 | — | — | — | NNW 4 | — | — | — | ESE 4 | ENE 5 | ENE 5 | SSE 4 |
| kJ | 26 | 11 | 57 | 79 | 53 | 24 | 11 | 43 | 48 | — | — | — | 3 | — | — | — | 13 | 17 | 17 | 1 |
Nearest Offshore or Glassy | ||||||||||||||||||||
Distance (km) | 244 | 830 | 167 | 506 | 185 | 185 | 284 | 187 | 232 | 277 | 178 | 178 | 324 | 158 | 256 | 259 | 261 | 326 | 258 | 326 |
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.
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