Surf Forecasts:
Cable Bay (Porth Trecastell) surf forecast from 5 Sep 2026:
- Most powerful swell: Thursday 10 Sep, 10PM (local time) - 5.5ft (1.7m), 6s period, SSW swell with 202 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 1.7m 6s and forecast to arrive on Thursday (Sep 10) at 10PM. Winds are predicted to be cross-onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.9m 5s period and expected on Saturday (Sep 12) at 4AM.
| Wave Type | Time (BST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | - | - |
| Best Surf | - | - |
| Most Powerful | 10PM (Thu 10th Sep) | 5.5ft (1.7m) 6s |
Table - best surf conditions forecast for Cable Bay (Porth Trecastell) over the next 16 days.
The Lowdown
Alright, Rusty here. Let's run through the numbers for Cable Bay.
Right now, it's a proper flat spell. For the next week and a half, there's nothing worth even thinking about. The wind is either too strong or from the wrong angle, and the swell is a mess. The first week is a total blank—no quality waves at all. The combined swell energy is weak, reading 27 on the 5th, and only getting up to 145 on the 6th, but it's all wind-chopped and lumpy. You'd be wasting your time.
Cable Bay (Porth Trecastell) is an exposed spot, but it's getting the wrong wind. The water is at 63°F, which is a touch warmer than normal for this time of year, but that doesn't help the waves. Things stay bleak through the 16th, a solid 10 days of no surf.
Now, finally, around Thursday, September 17th, there's a glimmer. We get a clean window with offshore winds from the NE at only 3 mph. The swell pushes up to 5 ft out of the west, with a period of 6 seconds. The combined energy hits 169 (moderate wave energy). It's not epic, but it's the first clean, surfable condition we've seen. The waves will be a bit short-period, so it's not going to be a long wall, but for a Thursday morning session, you'll get some fun ones. The wind is off, so it’ll be glassy. This is the best of the batch, but it's only a "1" on the quality scale, so keep your expectations in check.
Friday the 18th shows a bit more swell energy at 196 (moderate), with 5 ft from the SW, but the wind turns slightly cross-onshore, making it marginal. The 19th is similar, but lighter. After that, it fades back to small and weak.
To sum it up, the only real chance to get wet is the morning of the 17th. It's been a long wait, and the rest of the 16 days is mostly a bust. Forecasts can change though, so keep an eye on it.
Rusty.
Short Range ForecastLight rain (total 9mm), mostly falling on Mon night. Warm (max 20°C on Sun afternoon, min 13°C on Mon night). Winds increasing (light winds from the W on Sun night, fresh winds from the W by Tue morning). | Days 5-7 Weather SummaryLight rain (total 4mm), mostly falling on Thu night. Very mild (max 17°C on Thu night, min 13°C on Tue night). Winds decreasing (fresh winds from the W on Tue afternoon, calm by Wed night). | |||||||||||||||||||
Sat 5 | Sunday 6 | Monday 7 | Tuesday 8 | Wednesday 9 | Thursday 10 | Friday 11 | ||||||||||||||
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 6 | SSW 4 | SSW 5 | SSW 6 | SW 6 | SW 14 | SW 5 | WSW 6 | WSW 5 | W 5 | NW 6 | NW 6 | WSW 4 | NW 4 | SW 4 | SSW 6 | SW 6 | SW 6 | SW 6 | NW 4 |
Wave Graph  | ||||||||||||||||||||
 kJ | 16 | 24 | 111 | 139 | 137 | 33 | 91 | 119 | 117 | 134 | 171 | 131 | 14 | 6 | 24 | 138 | 152 | 37 | 30 | 37 |
Wind (km/h) | ||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | on | cross-on | cross-on | cross-on | on | on | on | cross-on | cross-on | cross-on | cross | cross | cross-on | glassy | cross-on | cross-on | on | cross | cross-on | cross |
High Tide | 4:06PM3.08m | 5:04AM3.02m | 5:48PM3.13m | 6:46AM3.12m | 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 | |||||||
Low Tide | 11:26PM1.19m | 12:11PM1.26m | 00:57AM0.99m | 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 | ||||||||
 |  |  | |  |  | |  | | |  |  | | | | | | | | | |
 | — | — | 6:35 | — | — | 6:35 | — | — | 6:37 | — | — | 6:39 | — | — | 6:41 | — | — | 6:43 | — | — |
 | 7:59 | — | — | 7:55 | — | — | 7:53 | — | — | 7:52 | — | — | 7:49 | — | — | 7:46 | — | — | 7:44 | — |
mm | — | 1 | 1 | — | — | — | 1 | 6 | — | — | — | — | — | — | — | — | 4 | — | — | — |
Temp °C | 14 | 15 | 18 | 20 | 17 | 15 | 16 | 14 | 14 | 15 | 14 | 14 | 15 | 16 | 16 | 16 | 17 | 14 | 16 | 15 |
Feels °C | 10 | 10 | 12 | 14 | 14 | 12 | 10 | 11 | 6 | 7 | 7 | 9 | 11 | 14 | 11 | 11 | 12 | 8 | 11 | 10 |
Swell 1 Height (m) Direction Period (s) | NW 4 | SW 13 | SW 13 | SW 13 | SW 12 | SW 14 | WNW 4 | SW 12 | — | — | SW 6 | SW 6 | NNW 5 | NW 4 | — | — | — | SW 6 | SW 6 | SW 7 |
| kJ | 4 | 7 | 7 | 6 | 6 | 33 | 1 | 6 | — | — | 26 | 11 | 32 | 6 | — | — | — | 37 | 30 | 21 |
Swell 2 Height (m) Direction Period (s) | NNW 5 | — | — | — | — | — | — | — | — | — | S 11 | — | SW 9 | SW 7 | — | — | — | — | — | — |
| kJ | 2 | — | — | — | — | — | — | — | — | — | 2 | — | 3 | 2 | — | — | — | — | — | — |
Swell 3 Height (m) Direction Period (s) | SW 13 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| kJ | 7 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
Wind waves Height (m) Direction Period (s) | SW 6 | SSW 4 | SSW 5 | SSW 6 | SW 6 | WSW 4 | SW 5 | WSW 6 | WSW 5 | W 5 | NW 6 | NW 6 | WSW 4 | SW 4 | SW 4 | SSW 6 | SW 6 | WNW 4 | WNW 4 | NW 4 |
| kJ | 16 | 24 | 111 | 139 | 137 | 25 | 91 | 119 | 117 | 134 | 171 | 131 | 14 | 4 | 24 | 138 | 152 | 24 | 25 | 37 |
Nearest Offshore or Glassy | ||||||||||||||||||||
Distance (km) | 244 | 179 | 231 | 437 | 212 | 44 | 504 | 283 | 541 | 541 | 338 | 329 | 272 | 172 | 231 | 277 | 333 | 541 | 541 | 173 |
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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