Surf Forecasts:
Cable Bay (Porth Trecastell) surf forecast from 4 Sep 2026:
- Most powerful swell: Thursday 10 Sep, 7AM (local time) - 6ft (1.9m), 6s period, SSW swell with 295 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 1.9m 6s and forecast to arrive on Thursday (Sep 10) at 7AM. Winds are predicted to be onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.3m 5s period and expected on Wednesday (Sep 09) at 7PM.
| Wave Type | Time (BST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | - | - |
| Best Surf | - | - |
| Most Powerful | 7AM (Thu 10th Sep) | 6ft (1.9m) 6s |
Table - best surf conditions forecast for Cable Bay (Porth Trecastell) over the next 16 days.
The Lowdown
Alright, Rusty here again. Let’s break this down for the imperial crew. It’s a grim 16-day forecast for Cable Bay (Porth Trecastell). Honestly, there’s a whole lot of nothing on offer for most of it, and the only real glimmer of hope is way out at the end.
The water is sitting at 63°, which is a touch warmer than average for this time of year, so you might get away with a thinner suit.
The first week is a right mess. Friday the 4th starts with a lumpy 6ft swell from the WSW, but a cross-on wind at 22 mph tears it apart. The combined energy is moderate at 184, but the quality is poor. Saturday the 5th is no better – a 3ft swell with a short 5-second period and a cross-on wind. Sunday the 6th is the same story: 5ft to 5ft swell with a fresh cross-on breeze, making for lumpy, poor surf. The energy never gets high enough to overcome the wind.
There’s a huge gap of several days where the swell drops to almost nothing, with just a few tiny, weak pulses. The wind finally turns clean and offshore on the 13th, but the swell is a pathetic 0.3ft.
Then, on Wednesday the 16th, something clicks. The afternoon shows a clean 6ft swell from the SW with a cross-off wind from the north at 22 mph. The combined energy jumps to a strong 306. The period is 6 seconds, which is short, but the clean conditions are a massive win. This is the true standout. For experienced surfers, this is the one to aim for. The wind is glassy and the swell has some size.
Thursday the 17th still has clean conditions, but the swell drops to 3ft to 4ft. Friday the 18th morning shows another pulse of 6ft with a clean cross-off breeze, but it’s only a marginal call.
So, the only real highlight is the afternoon of Wednesday the 16th. That’s your best shot. The rest of the run is almost entirely flat or blown out. It’s a tough outlook, but things can change. For now, circle that Wednesday.
Rusty.
Short Range ForecastLight rain (total 5mm), mostly falling on Sat night. Very mild (max 19°C on Sun afternoon, min 13°C on Fri night). Mainly fresh winds. | Days 4-6 Weather SummaryLight rain (total 6mm), mostly falling on Wed night. Very mild (max 16°C on Mon afternoon, min 13°C on Mon night). Winds decreasing (strong winds from the SSW on Mon afternoon, light winds from the SW by Wed night). | ||||||||||||||||||||
Friday 4 | Saturday 5 | Sunday 6 | Monday 7 | Tuesday 8 | Wednesday 9 | Thursday 10 | |||||||||||||||
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) | WSW 5 | WSW 6 | W 5 | W 5 | SW 6 | SSW 4 | SSW 6 | SSW 6 | SW 6 | SW 14 | SW 5 | WSW 6 | WSW 6 | WSW 6 | WNW 6 | WNW 5 | W 5 | SSW 5 | SSW 6 | SW 7 | W 5 |
Wave Graph  | |||||||||||||||||||||
 kJ | 176 | 119 | 117 | 47 | 26 | 44 | 122 | 156 | 112 | 42 | 166 | 243 | 223 | 143 | 167 | 106 | 46 | 83 | 176 | 111 | 52 |
Wind (km/h) | |||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross-on | cross-on | cross-on | cross-on | on | cross-on | cross-on | cross-on | on | on | on | cross-on | cross-on | cross-on | cross-on | cross-on | on | cross-on | on | on | cross-on |
High Tide | 2:44PM3.26m | 3:24AM3.18m | 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 | ||||||||
Low Tide | 9:57PM1.11m | 10:40AM1.25m | 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 | |||||||||
 | |  |  | |  | |  |  | | |  |  | | | | | | | | | |
 | 6:31 | — | — | 6:33 | — | — | 6:35 | — | — | 6:35 | — | — | 6:37 | — | — | 6:39 | — | — | 6:41 | — | — |
 | — | 8:00 | — | — | 7:59 | — | — | 7:55 | — | — | 7:53 | — | — | 7:52 | — | — | 7:49 | — | — | 7:46 | — |
mm | — | — | — | — | — | 5 | — | — | — | — | — | 1 | 1 | — | — | — | — | 4 | — | — | — |
Temp °C | 16 | 17 | 16 | 14 | 15 | 15 | 18 | 19 | 17 | 15 | 16 | 13 | 14 | 15 | 14 | 14 | 15 | 16 | 17 | 18 | 17 |
Feels °C | 10 | 12 | 10 | 11 | 11 | 11 | 11 | 13 | 13 | 11 | 8 | 7 | 6 | 7 | 7 | 8 | 10 | 14 | 14 | 13 | 12 |
Swell 1 Height (m) Direction Period (s) | SW 14 | SW 14 | SW 14 | SW 14 | NW 4 | — | SW 13 | SW 13 | SW 6 | SW 14 | — | — | — | SW 11 | — | S 10 | — | — | — | — | SW 7 |
| kJ | 8 | 8 | 8 | 7 | 4 | — | 7 | 6 | 112 | 32 | — | — | — | 5 | — | 2 | — | — | — | — | 25 |
Swell 2 Height (m) Direction Period (s) | — | — | — | — | NNW 5 | — | — | — | SW 12 | — | — | — | — | — | — | — | — | — | — | — | — |
| kJ | — | — | — | — | 2 | — | — | — | 6 | — | — | — | — | — | — | — | — | — | — | — | — |
Swell 3 Height (m) Direction Period (s) | — | — | — | — | SW 13 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| kJ | — | — | — | — | 7 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
Wind waves Height (m) Direction Period (s) | WSW 5 | WSW 6 | W 5 | W 5 | SW 6 | SSW 4 | SSW 6 | SSW 6 | — | WSW 4 | SW 5 | WSW 6 | WSW 6 | WSW 6 | WNW 6 | WNW 5 | W 5 | SSW 5 | SSW 6 | SW 7 | W 5 |
| kJ | 176 | 119 | 117 | 47 | 26 | 44 | 122 | 156 | — | 42 | 166 | 243 | 223 | 143 | 167 | 106 | 46 | 83 | 176 | 111 | 52 |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 297 | 506 | 173 | 185 | 244 | 179 | 231 | 341 | 118 | 44 | 319 | 167 | 795 | 507 | 384 | 295 | 261 | 262 | 163 | 319 | 541 |
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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