Surf Forecasts:
Trearddur Bay (Holy Island) surf forecast from 13 Sep 2026:
- Most powerful swell: Friday 18 Sep, 7PM (local time) - 8ft (2.5m), 7s period, SW swell with 708 kJ wave energy.
Best Forecast Surf Conditions for Trearddur Bay (Holy Island) this week:
The most powerful waves expected at Trearddur Bay (Holy Island) in the next 16 days are 2.5m 7s and forecast to arrive on Friday (Sep 18) at 7PM. 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 10AM.
| Wave Type | Time (BST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | - | - |
| Best Surf | - | - |
| Most Powerful | 7PM (Fri 18th Sep) | 8ft (2.5m) 7s |
Table - best surf conditions forecast for Trearddur Bay (Holy Island) over the next 16 days.
The Lowdown
Right then, let’s have a look at what Trearddur Bay (Holy Island) has in store.
Honestly, mate, I’m looking at the next sixteen days and it’s a tough stretch. The swell energy is weak to moderate at best, and the wind is just messy for most of it. We’ve got a long dry spell here with no proper surf on offer until the tail end.
Sunday the 13th and Monday the 14th are a write-off – tiny waves with poor conditions. The swell is only 2ft and 2ft, short period around 5-6 seconds, and the wind is cross or cross-onshore. Not worth paddling out.
Tuesday the 15th through to Sunday the 20th sees a bit more energy, with wave heights creeping up to 6ft. But the wind is cross-on or onshore and strong, making it messy and lumpy. Thursday the 17th has a 5ft swell from the W but with a moderate cross-onshore breeze. Friday the 18th has the biggest swell of the period at 6ft from the SW, but with a near gale blowing 34 mph onshore – that’s blown out, and probably only for experts if you’re desperate. For most, it looks more interesting for kite surfing than paddle surfing.
We then hit a gap from Monday the 21st to Wednesday the 23rd where the swell drops right off, with tiny waves under 2ft and light cross-onshore winds.
Now, there is a light at the end of the tunnel. Thursday the 24th and Friday the 25th finally offer something clean. Thursday morning we get a 3ft swell from the NW, and the wind is offshore from the NE at just 3 mph. That’s clean surf. The water temperature is a touch warmer than normal for the time of year, sitting around 62°F. Friday the 25th morning is glassy with a 2ft WNW swell and no wind – dead flat calm, perfect conditions for a beginner-friendly wave. The swell period is short (4 seconds), so it won’t have much punch, but for a small, clean wave, it’s the pick of the bunch.
After that, Saturday the 26th and Sunday the 27th see the wind shift onshore again, and the swell drops away. Sunday afternoon the 27th has a 4ft WNW swell with a fresh cross-offshore wind, but that’s still a bit lumpy. Monday the 28th is cross-shore and messy again.
So, the standout here is the 25th of September – Friday morning. It’s the only time we get glassy conditions and a rideable wave. It’s small, but it’ll be clean. If you’re a beginner, that’s your window. Trearddur Bay is inconsistent at the best of times, and this forecast reflects that. It’s a long blank run, but when the wind finally plays ball, it’ll be worth a session.
Rusty.
Short Range ForecastLight rain (total 5mm), mostly falling on Mon night. Very mild (max 17°C on Sun afternoon, min 13°C on Tue night). Winds increasing (light winds from the WSW on Sun afternoon, strong winds from the SSW by Mon night). | Days 4-6 Weather SummaryLight rain (total 4mm), mostly falling on Wed night. Very mild (max 16°C on Fri afternoon, min 12°C on Wed morning). Winds increasing (light winds from the SW on Wed afternoon, near gales from the SW by Fri afternoon). | ||||||||||||||||||||
Sunday 13 | Monday 14 | Tuesday 15 | Wednesday 16 | Thursday 17 | Friday 18 | Saturday 19 | |||||||||||||||
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 | SW 6 | SSW 4 | SW 5 | SSW 5 | SW 6 | WSW 6 | W 5 | NW 5 | SW 6 | SW 11 | SW 5 | WNW 5 | W 5 | W 6 | WSW 6 | SW 6 | WSW 7 | SW 7 | SW 7 | SSW 7 |
Wave Graph  | |||||||||||||||||||||
 kJ | 25 | 18 | 11 | 23 | 63 | 293 | 107 | 60 | 106 | 6 | 5 | 60 | 77 | 119 | 152 | 167 | 247 | 342 | 85 | 231 | 90 |
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 | cross | cross | on | cross | cross-on | cross-on | on | on | cross-on | cross-on | cross-on | cross-on |
High Tide | 12:25PM5.56m | 00:40AM5.77m | 1:00PM5.44m | 1:15AM5.55m | 1:34PM5.27m | 1:50AM5.26m | 2:09PM5.06m | 2:27AM4.94m | 2:48PM4.82m | 3:10AM4.60m | 3:35PM4.56m | 4:07AM4.26m | 4:41PM4.33m | ||||||||
Low Tide | 6:26PM0.74m | 6:52AM0.70m | 7:02PM0.91m | 7:27AM0.99m | 7:38PM1.17m | 8:03AM1.34m | 8:16PM1.50m | 8:40AM1.73m | 8:59PM1.87m | 9:24AM2.12m | 9:53PM2.22m | 10:24AM2.47m | 11:11PM2.48m | ||||||||
 | |  | | |  | |  | |  | |  | | | | |  | | | | | |
 | 6:47 | — | — | 6:48 | — | — | 6:50 | — | — | 6:52 | — | — | 6:54 | — | — | 6:56 | — | — | 6:56 | — | — |
 | — | 7:39 | — | — | 7:37 | — | — | 7:35 | — | — | 7:32 | — | — | 7:30 | — | — | 7:28 | — | — | 7:24 | — |
mm | — | — | — | — | — | 4 | — | 1 | — | — | — | 3 | — | — | — | — | 1 | — | — | — | — |
Temp °C | 16 | 17 | 17 | 17 | 17 | 17 | 14 | 16 | 15 | 13 | 15 | 15 | 14 | 15 | 14 | 15 | 16 | 15 | 15 | 16 | 15 |
Feels °C | 15 | 16 | 16 | 15 | 12 | 11 | 8 | 11 | 9 | 7 | 12 | 11 | 8 | 10 | 8 | 6 | 9 | 8 | 8 | 9 | 9 |
Swell 1 Height (m) Direction Period (s) | SSW 6 | SW 6 | — | — | SW 12 | — | — | — | SW 6 | SW 6 | SW 6 | NNW 5 | SW 6 | — | — | — | — | — | NW 5 | SW 7 | SSW 7 |
| kJ | 25 | 18 | — | — | 6 | — | — | — | 9 | 6 | 1 | 2 | 66 | — | — | — | — | — | 23 | 231 | 90 |
Swell 2 Height (m) Direction Period (s) | — | — | — | — | — | — | — | S 11 | S 11 | SW 11 | — | — | — | — | — | — | — | — | NW 5 | — | — |
| kJ | — | — | — | — | — | — | — | 2 | 2 | 5 | — | — | — | — | — | — | — | — | 18 | — | — |
Swell 3 Height (m) Direction Period (s) | — | — | — | — | — | — | — | — | — | — | SW 11 | — | — | — | — | — | — | — | — | — | — |
| kJ | — | — | — | — | — | — | — | — | — | — | 5 | — | — | — | — | — | — | — | — | — | — |
Wind waves Height (m) Direction Period (s) | — | — | SSW 4 | SW 5 | SSW 5 | SW 6 | WSW 6 | W 5 | NW 5 | NW 6 | NW 6 | SW 5 | WNW 5 | W 5 | W 6 | WSW 6 | SW 6 | WSW 7 | SW 7 | — | WNW 4 |
| kJ | — | — | 11 | 23 | 63 | 293 | 107 | 60 | 106 | 141 | 67 | 60 | 77 | 119 | 152 | 167 | 247 | 342 | 85 | — | 10 |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 208 | 246 | 246 | 246 | 246 | 305 | 548 | 626 | 346 | 346 | 51 | 246 | 284 | 299 | 179 | 517 | 838 | 838 | 897 | 280 | 251 |
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 Trearddur Bay (Holy Island) Surf forecast
The above surf forecast table for Trearddur Bay (Holy Island) provides essential information for determining whether the surfing conditions will be good over the next 16 days. A general guide to surfing at Trearddur Bay (Holy Island) can be found by selecting the local surf guide option on the grey menu. Our Trearddur Bay (Holy Island) 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 (Trearddur Bay (Holy Island)) 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 Trearddur Bay (Holy Island) 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 Trearddur Bay (Holy Island), camping, hotels and holiday cottages in Anglesy, consider staying in Holyhead 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 Anglesey which is 7 km (4 miles) away, Bangor, Porthmadog and Llandudno.
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