Surf Forecasts:
Cable Bay (Porth Trecastell) surf forecast from 7 Sep 2026:
- Most powerful swell: Saturday 12 Sep, 7PM (local time) - 7ft (2.2m), 7s period, SW swell with 412 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 2.2m 7s and forecast to arrive on Saturday (Sep 12) 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 1.7m 6s period and expected on Wednesday (Sep 09) at 1AM.
| Wave Type | Time (BST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | - | - |
| Best Surf | - | - |
| Most Powerful | 7PM (Sat 12th Sep) | 7ft (2.2m) 7s |
Table - best surf conditions forecast for Cable Bay (Porth Trecastell) over the next 16 days.
The Lowdown
Alright folks, Rusty here. Grab a coffee, because we’re looking at a pretty bleak run of surf ahead for Cable Bay. The short story is, don’t bother paddling out for the next week and a half. The big picture is small, weak swell combined with onshore wind nearly every day, churning up nothing but mess. We’re talking two full weeks with no good surf to speak of.
Looking at the immediate period, from the 7th of September right through to the morning of the 17th, it's just constant poor surf conditions. We've got a tiny, weak pulse of 3 to 5 ft swell from the SW and WSW, but it’s a short-period windswell at only 4-5 seconds, and the wind is smashing it onshore from the SW and WNW. The combined energy is weak, ranging from around 67 right up to a still-modest 176 on the 10th, but the wind just won't let up. The water temp is 63°, which is a touch warmer than normal for this time of year, but you won’t be feeling it from the beach here.
The only sliver of light, and I mean a sliver, comes on the morning of Saturday, the 19th of September. The forecast shows a decent pulse of swell hitting 6 ft from the SW, with a period of 6 seconds and combined energy of 236 – that’s the only period that even flirts with moderate energy. The key is the wind: it's a light ESE breeze going cross-offshore, which will clean the waves right up. That morning session at Cable Bay (Porth Trecastell) looks like a real stand-out, but only for that one short window. By the afternoon the wind swings onshore and it’s back to choppy mush.
Before that, on the 17th, there’s a pulse of 7 ft to 6 ft SSW swell with a 6-second period. It’s bigger, with energy hitting 603 on the afternoon, but it’s cross-shore and the data says it’s only marginal, not good. It’s too stormy and likely a close-out for most.
Honestly, mate, for the next 16 days, your best bet is to plan for that Saturday morning, the 19th. It’s a long way out, so keep an eye on it, but it's the only real highlight in a very quiet outlook. For the rest of it, the kite boarders might get more out of this onshore slop than we will.
Rusty
Short Range ForecastLight rain (total 3mm), mostly falling on Mon night. Very mild (max 16°C on Mon afternoon, min 13°C on Mon night). Mainly strong winds. | Days 4-6 Weather SummaryModerate rain (total 10mm), heaviest on Sat afternoon. Very mild (max 18°C on Sat night, min 14°C on Thu night). Winds increasing (calm on Fri afternoon, strong winds from the SSW by Sat afternoon). | ||||||||||||||||||||
Monday 7 | Tuesday 8 | Wednesday 9 | Thursday 10 | Friday 11 | Saturday 12 | Sunday 13 | |||||||||||||||
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 14 | SW 5 | SW 7 | W 5 | WNW 5 | SW 6 | SW 7 | SW 7 | SW 4 | SW 4 | SSW 6 | SW 6 | SW 6 | SW 6 | SW 3 | SSW 5 | SSW 6 | SW 7 | SW 7 | SSW 6 | SSW 5 |
Wave Graph  | |||||||||||||||||||||
 kJ | 34 | 94 | 163 | 81 | 105 | 5 | 19 | 14 | 11 | 40 | 176 | 120 | 33 | 19 | 12 | 116 | 406 | 173 | 44 | 35 | 46 |
Wind (km/h) | |||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | on | on | cross-on | cross-on | cross-on | cross | cross | on | on | cross-on | on | on | cross | cross | cross-on | cross-on | cross-on | on | cross | cross-on | cross-on |
High Tide | 7:12PM3.41m | 7:58AM3.37m | 8:11PM3.77m | 8:48AM3.63m | 8:58PM4.11m | 9:29AM3.86m | 9:39PM4.37m | 10:06AM4.03m | 10:17PM4.51m | 10:42AM4.11m | 10:54PM4.52m | 11:16AM4.11m | 11:30PM4.39m | ||||||||
Low Tide | 1:29PM1.03m | 2:07AM0.62m | 2:30PM0.70m | 3:02AM0.22m | 3:19PM0.38m | 3:49AM-0.10m | 4:02PM0.12m | 4:31AM-0.30m | 4:43PM-0.03m | 5:10AM-0.34m | 5:22PM-0.06m | 5:48AM-0.24m | 5:59PM0.01m | ||||||||
 |  |  |  | |  | | | | | |  | | |  |  |  | | | | | |
 | 6:35 | — | — | 6:37 | — | — | 6:39 | — | — | 6:41 | — | — | 6:43 | — | — | 6:45 | — | — | 6:47 | — | — |
 | — | 7:53 | — | — | 7:52 | — | — | 7:49 | — | — | 7:46 | — | — | 7:44 | — | — | 7:42 | — | — | 7:38 | — |
mm | — | 1 | 2 | — | — | — | — | — | — | — | — | 2 | — | — | — | 1 | 6 | 1 | 1 | — | — |
Temp °C | 15 | 16 | 14 | 14 | 16 | 14 | 13 | 14 | 15 | 16 | 16 | 17 | 14 | 15 | 14 | 14 | 15 | 18 | 16 | 16 | 15 |
Feels °C | 11 | 11 | 10 | 7 | 9 | 7 | 8 | 11 | 11 | 10 | 10 | 14 | 10 | 13 | 11 | 7 | 8 | 15 | 14 | 14 | 13 |
Swell 1 Height (m) Direction Period (s) | SW 14 | — | SW 7 | SW 12 | SW 11 | SW 6 | SW 7 | N 5 | SSW 7 | — | — | SW 6 | SW 6 | SW 6 | — | — | — | SW 7 | SW 7 | NNW 5 | — |
| kJ | 33 | — | 163 | 5 | 5 | 5 | 19 | 18 | 5 | — | — | 120 | 33 | 19 | — | — | — | 173 | 44 | 4 | — |
Swell 2 Height (m) Direction Period (s) | — | — | SW 12 | SW 11 | SW 10 | SW 10 | — | W 4 | N 4 | — | — | — | — | — | — | — | — | — | NW 4 | — | — |
| kJ | — | — | 6 | 5 | 4 | 4 | — | 2 | 1 | — | — | — | — | — | — | — | — | — | 11 | — | — |
Swell 3 Height (m) Direction Period (s) | — | — | — | — | — | — | — | SW 7 | — | — | — | — | — | — | — | — | — | — | — | S 13 | — |
| kJ | — | — | — | — | — | — | — | 14 | — | — | — | — | — | — | — | — | — | — | — | 3 | — |
Wind waves Height (m) Direction Period (s) | WSW 4 | SW 5 | NW 4 | W 5 | WNW 5 | NW 6 | NNW 6 | — | SW 4 | SW 4 | SSW 6 | — | NW 4 | NW 4 | SW 3 | SSW 5 | SSW 6 | — | — | SSW 6 | SSW 5 |
| kJ | 34 | 94 | 9 | 81 | 105 | 198 | 77 | — | 11 | 40 | 176 | — | 24 | 7 | 12 | 116 | 406 | — | — | 35 | 46 |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 44 | 319 | 221 | 173 | 1086 | 338 | 181 | 260 | 186 | 277 | 277 | 168 | 172 | 187 | 172 | 231 | 256 | 261 | 308 | 285 | 179 |
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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