Surf Forecasts:
Cable Bay (Porth Trecastell) surf forecast from 11 Aug 2026:
- Most powerful swell: Friday 14 Aug, 1AM (local time) - 2.5ft (0.8m), 5s period, SW swell with 34 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 0.8m 5s and forecast to arrive on Friday (Aug 14) at 1AM. Winds are predicted to be cross-onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.6m 4s period and expected on Saturday (Aug 15) at 1PM.
| Wave Type | Time (BST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | - | - |
| Best Surf | - | - |
| Most Powerful | 1AM (Fri 14th Aug) | 2.5ft (0.8m) 5s |
Table - best surf conditions forecast for Cable Bay (Porth Trecastell) over the next 16 days.
The Lowdown
Alright, Rusty here again. Let’s talk about what’s going down at Cable Bay (Porth Trecastrell) in feet and miles per hour.
I’ve got to level with you: the start of this forecast is a total bust. For the first week and a half, the ocean has given up. We’re looking at wave heights barely hitting `1 ft`, with terrible swell periods and almost no energy – the combined energy numbers are mostly in the single digits or low teens. The water is `64°F`, which is about `4°F` warmer than usual for this time of year, so it’s nice for a swim, but that’s about it. Through Thursday 14 August, the wind is onshore or cross-onshore, making everything flat or choppy.
There’s a tiny spike on Friday 14 August with a `3 ft` NW swell, but the period is super short and it’s cross-shore. Not worth the drive.
Monday 17 August gives us offshore wind (ENE `12 mph`) and clean conditions, but the swell is only `1 ft`. Glassy, but nothing to ride.
Now, the only real event on the calendar is way out there, on Sunday 23 August. We get a `5 ft` SSW swell building through the morning. The period is short, about `7 seconds`, so it’ll be a bit jumbled. The combined energy hits `265` – finally, some moderate power! But the wind is onshore from the SW at `16 mph`, making it bumpy. By the afternoon, the swell hits `6 ft` with the wind picking up to `21 mph` from the south, creating a lumpy, cross-onshore mess.
Monday 24 August brings the biggest swell of the period – a solid `8 ft` from the SW, with an energy reading of `890`, which is strong. That’s too big for anyone but experts. The period is still short at `9 seconds`, and the wind is a near-gale at `30 mph` from the WNW. This is purely blown-out and messy. Kite surfers might have a field day, but for a regular surfer? Forget it.
So here’s the bottom line: Over the next 16 days, there is no window where the waves, wind, and conditions all line up. The only real pulse of swell is that Sunday/Monday window, but the wind is going to trash it. If you’re a die-hard, maybe paddle out Monday morning with a big board and low expectations, but this is a tough stretch. It happens. The sea will wake up again.
Rusty.
Short Range ForecastMostly dry. Warm (max 25°C on Wed afternoon, min 17°C on Thu night). Wind will be generally light. | Days 4-6 Weather SummaryLight rain (total 2mm), mostly falling on Sun afternoon. Very mild (max 18°C on Fri night, min 14°C on Sun afternoon). Wind will be generally light. | ||||||||||||||||||||
Tuesday 11 | Wednesday 12 | Thursday 13 | Friday 14 | Saturday 15 | Sunday 16 | Monday 17 | |||||||||||||||
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 6 | SSW 3 | S 11 | SW 12 | SW 12 | SW 10 | SW 10 | SW 11 | SW 5 | NW 4 | WNW 4 | SSW 6 | NW 4 | WNW 4 | W 3 | SW 4 | SW 4 | SSW 3 | SSW 4 | SW 4 | SSW 5 |
Wave Graph  | |||||||||||||||||||||
 kJ | 4 | 2 | 2 | 6 | 6 | 4 | 4 | 4 | 34 | 28 | 6 | 4 | 16 | 2 | 1 | 1 | 1 | 1 | 6 | 5 | 3 |
Wind (km/h) | |||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross-on | on | cross | cross-on | cross-on | cross-on | on | on | cross-on | cross | cross | cross | cross | cross | glassy | cross-on | cross-on | off | off | off | off |
High Tide | 9:07PM4.05m | 9:40AM3.86m | 9:54PM4.35m | 10:25AM4.00m | 10:38PM4.54m | 11:07AM4.05m | 11:19PM4.59m | 11:46AM4.02m | 00:00AM4.50m | 12:25PM3.91m | 00:40AM4.27m | 1:04PM3.73m | 1:21AM3.95m | ||||||||
Low Tide | 3:34PM0.38m | 4:04AM-0.04m | 4:20PM0.13m | 4:50AM-0.29m | 5:04PM-0.02m | 5:34AM-0.40m | 5:45PM-0.06m | 6:15AM-0.35m | 6:25PM0.02m | 6:55AM-0.16m | 7:05PM0.20m | 7:34AM0.15m | 7:45PM0.46m | ||||||||
 |  |  | | |  | | | | | | | | | |  |  |  | | | | |
 | 5:50 | — | — | 5:52 | — | — | 5:52 | — | — | 5:54 | — | — | 5:56 | — | — | 5:58 | — | — | 6:00 | — | — |
 | — | 8:54 | — | — | 8:52 | — | — | 8:50 | — | — | 8:47 | — | — | 8:45 | — | — | 8:44 | — | — | 8:42 | — |
mm | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 2 | — | — | — | — |
Temp °C | 21 | 21 | 20 | 23 | 25 | 24 | 22 | 22 | 20 | 16 | 17 | 18 | 16 | 17 | 16 | 16 | 14 | 15 | 17 | 17 | 15 |
Feels °C | 17 | 18 | 19 | 20 | 22 | 23 | 22 | 21 | 20 | 14 | 14 | 14 | 13 | 15 | 15 | 14 | 13 | 15 | 13 | 12 | 12 |
Swell 1 Height (m) Direction Period (s) | SSW 6 | SW 6 | SSW 3 | SW 12 | SSW 3 | SW 5 | SW 8 | SW 11 | SW 5 | SW 5 | N 4 | SSW 6 | SW 5 | NNW 4 | W 3 | SW 4 | SW 4 | — | SSW 4 | SW 4 | SSW 5 |
| kJ | 4 | 1 | 1 | 5 | 1 | 1 | 3 | 4 | 34 | 6 | 3 | 4 | 1 | 6 | 1 | 1 | 1 | — | 6 | 5 | 3 |
Swell 2 Height (m) Direction Period (s) | — | — | SW 6 | SW 12 | SW 12 | SW 10 | SW 5 | S 11 | S 11 | — | SW 5 | — | — | SW 6 | S 5 | — | — | — | — | — | N 3 |
| kJ | — | — | 1 | 6 | 6 | 4 | 1 | 2 | 2 | — | 3 | — | — | 1 | 1 | — | — | — | — | — | 1 |
Swell 3 Height (m) Direction Period (s) | — | — | S 11 | W 10 | SW 6 | — | SW 10 | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| kJ | — | — | 2 | 2 | 1 | — | 4 | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
Wind waves Height (m) Direction Period (s) | — | SSW 3 | — | SSW 3 | — | — | SSW 2 | SW 2 | — | NW 4 | WNW 4 | NW 3 | NW 4 | WNW 4 | — | — | — | SSW 3 | — | NNE 3 | — |
| kJ | — | 2 | — | 3 | — | — | 1 | 1 | — | 28 | 6 | 5 | 16 | 2 | — | — | — | 1 | — | 4 | — |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 283 | 316 | 158 | 157 | 176 | 172 | 173 | 258 | 185 | 185 | 157 | 185 | 172 | 352 | 187 | 256 | 259 | 294 | 158 | 172 | 158 |
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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