Surf Forecasts:
Cable Bay (Porth Trecastell) surf forecast from 11 Aug 2026:
- Most powerful swell: Tuesday 18 Aug, 4PM (local time) - 3ft (0.9m), 5s period, SW swell with 31 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 0.9m 5s and forecast to arrive on Tuesday (Aug 18) at 4PM. Winds are predicted to be onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.8m 4s period and expected on Saturday (Aug 15) at 4AM.
| Wave Type | Time (BST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | - | - |
| Best Surf | - | - |
| Most Powerful | 4PM (Tue 18th Aug) | 3ft (0.9m) 5s |
Table - best surf conditions forecast for Cable Bay (Porth Trecastell) over the next 16 days.
The Lowdown
Alright folks, Rusty here. Gotta be straight with you—this 16-day window for Cable Bay is a tough one. We’re looking at a long, dry spell with barely a ripple to get excited about for the first couple of weeks. The water is running about 64° right now, which is much warmer than usual for this time of year, so at least you won't be cold while you're staring at a flat ocean.
The pattern is grim for a while. From Tuesday the 11th right through to the morning of Saturday the 22nd, it’s all tiny, weak, and mostly messy. We’re talking swell heights barely hitting 1 ft, with periods that are either way too short or way too long for the size. The combined energy is just pathetic—mostly single-digit numbers (2, 8, 11) that won't push a leaf. Winds are all over the shop, mostly onshore or cross, killing any chance of a clean wave. The 16th to the 19th is a total dead zone with zero swell at times. It’s a proper blank run.
There’s a tiny flicker of hope on Monday the 24th. Monday morning sees a jump in swell to 5 ft with a moderate offshore wind from the NE. The combined energy hits 155, which is moderate, and it's clean. The swell direction is SSW, which is close to that optimum SW direction for Cable Bay. This is the best on offer, but it’s still only rated as “surfable waves but very ordinary conditions.” Monday afternoon drops off a bit. Honestly, for a break that’s fairly consistent, this is a rough patch.
The real standout, and the one I’m pinning my hopes on, is Wednesday the 26th. That morning looks glassy with light rain and a light easterly breeze. The swell is a solid 7 ft from the SW with a period of 7 seconds. The combined energy jumps to 385, which is strong. That’s a proper swell for this spot. Now, 7 ft is getting into the expert-only zone, and the short period means it’ll be a bit crumbly, but with glassy conditions and that size, it’s the only time in the whole forecast that looks genuinely good. The afternoon is still surfable at 6 ft, but the wind swings onshore, messing it up a bit. For a break that can get crowded sometimes, that Wednesday morning session is the one to circle.
So, to sum it up: a whole lot of nothing for two weeks, then a promising but still uncertain window around the 24th, and one potentially great morning on the 26th. Keep your eyes on that forecast.
Rusty.
Short Range ForecastSome drizzle, heaviest during Fri morning. Warm (max 26°C on Wed afternoon, min 16°C on Fri morning). Wind will be generally light. | Days 5-7 Weather SummaryMostly dry. Very mild (max 18°C on Fri afternoon, min 13°C on Sat night). Wind will be generally light. | |||||||||||||||||||
Tue 11 | Wednesday 12 | Thursday 13 | Friday 14 | Saturday 15 | Sunday 16 | Monday 17 | ||||||||||||||
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) | S 3 | S 11 | SW 12 | SW 12 | SW 10 | SW 10 | SW 11 | SW 4 | SSW 5 | SW 5 | SW 6 | SW 6 | SW 6 | SW 7 | W 7 | NNW 4 | N 4 | NNW 4 | NNW 3 | — |
Wave Graph  | ||||||||||||||||||||
 kJ | 1 | 2 | 6 | 6 | 4 | 4 | 4 | 9 | 9 | 4 | 1 | 1 | 1 | 2 | 1 | 0 | 0 | 0 | 0 | 0 |
Wind (km/h) | ||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | on | glassy | cross-on | cross-on | cross-on | on | on | cross | cross | cross-off | cross-off | cross-off | cross-off | off | cross-off | cross | off | off | cross-off | glassy |
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 | 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 | ||||||||
 |  | |  | | | |  |  | | | | | | |  |  | | | | |
 | — | — | 5:52 | — | — | 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 | — | — | — | — | — | — | — | — | 1 | — | — | — | — | — | — | — | — | — | — | — |
Temp °C | 21 | 21 | 23 | 26 | 24 | 22 | 22 | 20 | 18 | 18 | 17 | 15 | 16 | 15 | 15 | 16 | 15 | 17 | 18 | 17 |
Feels °C | 19 | 21 | 20 | 24 | 23 | 20 | 22 | 21 | 19 | 15 | 15 | 10 | 12 | 12 | 12 | 14 | 13 | 14 | 15 | 16 |
Swell 1 Height (m) Direction Period (s) | SW 6 | — | SW 12 | SSW 3 | SW 5 | SW 8 | SW 8 | SW 4 | SSW 5 | SW 5 | SW 6 | SW 6 | SW 6 | — | W 7 | NNW 4 | — | NNW 4 | — | — |
| kJ | 1 | — | 6 | 1 | 1 | 3 | 2 | 9 | 9 | 4 | 1 | 1 | 1 | — | 1 | 6 | — | 2 | — | — |
Swell 2 Height (m) Direction Period (s) | — | SW 6 | SW 6 | SW 12 | SW 10 | SW 5 | SW 11 | S 11 | — | — | — | — | — | SW 7 | — | — | — | — | — | — |
| kJ | — | 1 | 1 | 6 | 4 | 1 | 4 | 2 | — | — | — | — | — | 2 | — | — | — | — | — | — |
Swell 3 Height (m) Direction Period (s) | — | S 11 | W 10 | SW 6 | — | SW 10 | S 11 | SW 11 | — | — | — | — | — | — | — | — | — | — | — | — |
| kJ | — | 2 | 2 | 1 | — | 4 | 2 | 5 | — | — | — | — | — | — | — | — | — | — | — | — |
Wind waves Height (m) Direction Period (s) | S 3 | — | SSW 3 | — | — | — | — | SSE 2 | WNW 3 | NW 4 | N 4 | NNW 5 | NNW 4 | N 4 | N 4 | — | N 4 | — | NNW 3 | — |
| kJ | 1 | — | 3 | — | — | — | — | 1 | 2 | 6 | 18 | 25 | 15 | 6 | 9 | — | 1 | — | 1 | — |
Nearest Offshore or Glassy | ||||||||||||||||||||
Distance (km) | 316 | 158 | 172 | 176 | 150 | 172 | 297 | 185 | 187 | 580 | 329 | 325 | 502 | 261 | 259 | 295 | 295 | 296 | 298 | 178 |
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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