Surf Forecasts:
Cable Bay (Porth Trecastell) surf forecast from 14 Sep 2026:
- Most powerful swell: Monday 14 Sep, 10PM (local time) - 6.5ft (2.0m), 6s period, SSW swell with 309 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 2.0m 6s and forecast to arrive on Monday (Sep 14) at 10PM. Winds are predicted to be onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 1.5m 6s period and expected on Wednesday (Sep 16) at 4AM.
| Wave Type | Time (BST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | - | - |
| Best Surf | - | - |
| Most Powerful | 10PM (Mon 14th Sep) | 6.5ft (2.0m) 6s |
Table - best surf conditions forecast for Cable Bay (Porth Trecastell) over the next 16 days.
The Lowdown
Alright, let me tell ya what I’m seeing for Cable Bay (Porth Trecastell) over the next couple of weeks. Honestly, it’s a bit of a rough stretch to start, but there’s a little light at the end of the tunnel if you’re patient.
Right off the bat, from Monday 14th September right through the week, it’s pretty grim. We’ve got a persistent cross-onshore wind, mostly from the S or WSW, blowing at 12 to 22 mph, which is making a mess of things. The swell is small and weak, mostly around 2 ft to 5 ft from the SSW or WSW, but the real problem is the period is super short – only 4 to 6 seconds. This is just windswell, no push, and the energy readings are low, mostly under 150 (weak). The surf is choppy, lumpy, and just not worth paddling out for. It stays like this, with that onshore flow, right into the weekend. Saturday 19th and Sunday 20th offer a slight glimmer – the swell gets a bit bigger, up to 6 ft from the SW on Saturday morning, and the wind actually drops to a gentle breeze on Saturday, and then a glassy moment on Sunday afternoon. But the surf is still described as marginal at best.
After a lull, things look more interesting around Tuesday 22nd September. The wind shifts to a light N cross-off, swinging to N at 9-12 mph, and the swell comes in from the W at 7 ft to 7 ft. The period stretches to 6 seconds – still not groundswell, but the energy is building, with readings of 304 and 353 (moderate). The wind is clean, and the surf is expected to be good. This is the standout window: it’s clean, it’s got some size, and after a week of chop, it’ll feel like a treat. That swell direction is SSW, which matches the exposure here nicely. Crowds? Cable Bay can get a few people on it, so don’t expect to be alone.
From Wednesday 23rd things drop off again into weak, small surf, and then the forecast throws a real curveball for Sunday 27th September. We’re looking at a big 10 ft SSW swell with a 7-second period and a combined energy of 853 (strong). That is a lot of water moving, and for a spot like this, it’s likely too big and too raw – not for beginners, really only for experts with a death wish, and even then, the report flags it as too big for this break. It’s not the best day to be out.
Overall, the first week is a write-off, the middle of the second week has a brief, clean window, and the very end of the outlook is either flat or oversized. Keep an eye on that Tuesday 22nd if you want to paddle out.
Rusty.
Short Range ForecastLight rain (total 4mm), mostly falling on Mon night. Very mild (max 17°C on Sun night, min 13°C on Tue night). Winds increasing (light winds from the S on Sun night, fresh winds from the SSW by Mon night). | Days 4-6 Weather SummaryLight rain (total 4mm), mostly falling on Wed night. Very mild (max 17°C on Sat afternoon, min 13°C on Wed night). Winds decreasing (fresh winds from the WSW on Wed night, light winds from the WSW by Sat afternoon). | ||||||||||||||||||||
Monday 14 | Tuesday 15 | Wednesday 16 | Thursday 17 | Friday 18 | Saturday 19 | Sunday 20 | |||||||||||||||
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) | SSW 5 | SSW 5 | SW 6 | WSW 5 | WSW 5 | SW 6 | SW 6 | W 4 | SW 5 | WSW 5 | WSW 5 | W 6 | W 6 | SW 5 | SW 6 | SW 6 | SW 7 | SW 7 | NW 5 | NW 5 | SSW 3 |
Wave Graph  | |||||||||||||||||||||
 kJ | 23 | 117 | 269 | 138 | 69 | 16 | 6 | 12 | 60 | 138 | 112 | 178 | 152 | 96 | 147 | 282 | 221 | 91 | 51 | 25 | 7 |
Wind (km/h) | |||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross-on | cross-on | on | cross-on | cross-on | cross | cross | cross-on | on | cross-on | cross-on | cross-on | cross-on | on | on | on | cross-on | cross-on | cross-on | glassy | cross-on |
High Tide | 11:50AM4.02m | 00:07AM4.16m | 12:24PM3.85m | 00:44AM3.84m | 1:00PM3.60m | 1:24AM3.48m | 1:40PM3.31m | 2:09AM3.11m | 2:30PM3.01m | 3:16AM2.79m | 3:54PM2.78m | 5:10AM2.63m | 5:52PM2.79m | ||||||||
Low Tide | 6:23AM-0.01m | 6:35PM0.19m | 6:58AM0.30m | 7:12PM0.44m | 7:33AM0.66m | 7:49PM0.75m | 8:09AM1.03m | 8:30PM1.08m | 8:52AM1.36m | 9:24PM1.38m | 9:52AM1.62m | 10:46PM1.58m | 11:27AM1.71m | 00:33AM1.54m | |||||||
 |  |  |  | |  | | | | |  | | |  | | | | | | | | |
 | 6:48 | — | — | 6:50 | — | — | 6:52 | — | — | 6:54 | — | — | 6:54 | — | — | 6:56 | — | — | 6:58 | — | — |
 | — | 7:37 | — | — | 7:35 | — | — | 7:31 | — | — | 7:30 | — | — | 7:27 | — | — | 7:24 | — | — | 7:22 | — |
mm | — | — | 4 | — | — | — | — | — | 1 | — | 1 | — | — | 1 | 1 | — | — | — | — | — | — |
Temp °C | 17 | 17 | 17 | 14 | 16 | 15 | 14 | 15 | 15 | 14 | 15 | 14 | 14 | 15 | 16 | 15 | 17 | 15 | 13 | 13 | 16 |
Feels °C | 16 | 12 | 12 | 8 | 12 | 10 | 8 | 10 | 10 | 8 | 10 | 8 | 10 | 9 | 13 | 12 | 14 | 11 | 12 | 12 | 12 |
Swell 1 Height (m) Direction Period (s) | — | SW 12 | — | — | — | SW 6 | SW 6 | NNW 6 | N 5 | — | — | — | — | NW 5 | — | — | — | SW 7 | SW 7 | NW 5 | NNW 4 |
| kJ | — | 6 | — | — | — | 16 | 6 | 31 | 2 | — | — | — | — | 9 | — | — | — | 91 | 21 | 25 | 2 |
Swell 2 Height (m) Direction Period (s) | — | — | — | — | — | SW 11 | SW 11 | NW 5 | — | — | — | — | — | — | — | — | — | — | S 14 | SW 6 | — |
| kJ | — | — | — | — | — | 5 | 5 | 1 | — | — | — | — | — | — | — | — | — | — | 4 | 10 | — |
Swell 3 Height (m) Direction Period (s) | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | S 14 | — |
| kJ | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 4 | — |
Wind waves Height (m) Direction Period (s) | SSW 5 | SSW 5 | SW 6 | WSW 5 | WSW 5 | NW 5 | NW 6 | W 4 | SW 5 | WSW 5 | WSW 5 | W 6 | W 6 | SW 5 | SW 6 | SW 6 | SW 7 | WNW 5 | NW 5 | — | SSW 3 |
| kJ | 23 | 117 | 269 | 138 | 69 | 92 | 124 | 12 | 60 | 138 | 112 | 178 | 152 | 96 | 147 | 282 | 221 | 67 | 51 | — | 7 |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 256 | 256 | 283 | 466 | 541 | 187 | 181 | 277 | 277 | 830 | 541 | 173 | 261 | 256 | 261 | 44 | 283 | 44 | 44 | 157 | 262 |
Best forecast wave conditions in Anglesy | |||||||||||||||||||||
Best forecast wave conditions in United Kingdom | |||||||||||||||||||||
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‘Porth Neigwl: Choppy waves hadn't tidied much (from what I could see in the dark.’
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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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