Surf Forecasts:
Trearddur Bay (Holy Island) surf forecast from 12 Aug 2026:
- Most powerful swell: Wednesday 19 Aug, 4AM (local time) - 5.5ft (1.7m), 5s period, WSW swell with 165 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 1.7m 5s and forecast to arrive on Wednesday (Aug 19) at 4AM. Winds are predicted to be onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 1.1m 5s period and expected on Saturday (Aug 15) at 7AM.
| Wave Type | Time (BST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | - | - |
| Best Surf | - | - |
| Most Powerful | 4AM (Wed 19th Aug) | 5.5ft (1.7m) 5s |
Table - best surf conditions forecast for Trearddur Bay (Holy Island) over the next 16 days.
The Lowdown
Alright, Rusty here. Let's have a look at what's on the cards for Trearddur Bay.
Well, I gotta be straight with you, the next week and a half or so is looking pretty grim. There’s almost nothing to get excited about. We're talking days of flat, choppy, or just plain messy conditions. The wind is mostly onshore or cross-onshore, and the swell is tiny. It’s a real dry spell.
The first real glimmer of hope doesn't show up until Saturday, August 22nd. Early that morning, we’ve got a tiny pulse of 4ft swell from the SSW, but the real kicker is the wind. It’s gonna be glassy. Absolutely dead calm. That’s a rare treat, and it’ll make the surface look like a mirror. The combined energy is weak (88), but for a beginner spot like Trearddur Bay, clean conditions trump everything. It’s the only standout in the whole outlook, and it’s purely for the morning glass-off. After that, the wind swings and the energy jumps up, but it gets messy again.
Later that same afternoon, Saturday the 22nd, the swell builds to 6ft from the S with a combined energy of 243, which is moderate. But the wind turns cross-onshore, so it’ll be a bit of a mess. That size is right on the edge of being too big for beginners anyway.
Before that, the only other thing worth mentioning is a brief window on Friday, August 14th afternoon. A tiny 1.0ft swell from the SW with a clean cross-offshore breeze. It’s clean, but there’s almost no energy in the water (combined energy of 3). More of a fun paddle than a proper surf.
The rest of the time is a write-off. You’ve got days of onshore wind, total flatness, and even a few proper storms rolling through with strong winds. For the first 10 days, it’s just a waiting game. The long-range stuff late in the month is too far out to bank on.
So, if you’re desperate, Saturday, August 22nd is your only real shot. Get there at dawn for the glass. After that, the forecast is a total blank.
Rusty.
Short Range ForecastMostly dry. Warm (max 25°C on Wed afternoon, min 16°C on Fri morning). Wind will be generally light. | Days 4-6 Weather SummaryLight rain (total 6mm), mostly falling on Mon morning. Very mild (max 16°C on Fri night, min 13°C on Fri night). Winds decreasing (fresh winds from the N on Fri night, calm by Sun night). | ||||||||||||||||||||
Wednesday 12 | Thursday 13 | Friday 14 | Saturday 15 | Sunday 16 | Monday 17 | Tuesday 18 | |||||||||||||||
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) | SW 12 | SW 12 | SW 11 | SW 11 | SW 11 | SW 4 | SW 5 | SW 5 | SW 6 | SW 6 | SW 6 | N 5 | W 7 | N 5 | W 7 | N 4 | SW 3 | SW 5 | SW 6 | SW 6 | WSW 5 |
Wave Graph  | |||||||||||||||||||||
 kJ | 6 | 6 | 4 | 5 | 4 | 16 | 6 | 3 | 2 | 1 | 2 | 0 | 1 | 0 | 1 | 0 | 4 | 55 | 110 | 86 | 95 |
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 | cross-off | cross-off | cross-off | cross-off | cross-off | cross-off | cross | glassy | cross-on | cross-on | on | cross-on | cross-on | on |
High Tide | 10:50AM5.42m | 11:07PM5.78m | 11:35AM5.56m | 11:49PM5.94m | 12:16PM5.58m | 00:30AM5.96m | 12:56PM5.52m | 1:10AM5.85m | 1:35PM5.37m | 1:49AM5.63m | 2:12PM5.16m | 2:28AM5.33m | 2:51PM4.93m | 3:07AM4.98m | |||||||
Low Tide | 4:33AM0.72m | 4:48PM0.94m | 5:19AM0.45m | 5:32PM0.74m | 6:02AM0.32m | 6:14PM0.67m | 6:44AM0.35m | 6:54PM0.71m | 7:25AM0.53m | 7:34PM0.87m | 8:05AM0.82m | 8:13PM1.14m | 8:44AM1.19m | 8:54PM1.47m | |||||||
 |  |  | | |  |  | | | | | | | |  |  | | | | | | |
 | 5:52 | — | — | 5:54 | — | — | 5:54 | — | — | 5:56 | — | — | 5:58 | — | — | 6:01 | — | — | 6:01 | — | — |
 | — | 8:52 | — | — | 8:51 | — | — | 8:49 | — | — | 8:46 | — | — | 8:45 | — | — | 8:43 | — | — | 8:40 | — |
mm | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 1 | 5 | — | — | — | 1 | 1 |
Temp °C | 22 | 25 | 24 | 22 | 22 | 20 | 17 | 17 | 16 | 14 | 15 | 15 | 14 | 16 | 15 | 13 | 14 | 15 | 17 | 17 | 17 |
Feels °C | 19 | 23 | 23 | 21 | 22 | 19 | 16 | 15 | 12 | 9 | 11 | 11 | 10 | 14 | 13 | 12 | 11 | 15 | 12 | 13 | 13 |
Swell 1 Height (m) Direction Period (s) | SW 12 | SSW 3 | SW 10 | SW 8 | SW 8 | SW 4 | SW 5 | SW 5 | SW 6 | SW 6 | SW 6 | — | W 7 | — | NNW 4 | N 4 | — | — | — | — | — |
| kJ | 6 | 2 | 4 | 3 | 2 | 16 | 6 | 3 | 2 | 1 | 2 | — | 1 | — | 6 | 1 | — | — | — | — | — |
Swell 2 Height (m) Direction Period (s) | S 6 | SW 12 | — | SW 5 | SW 11 | S 11 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| kJ | 1 | 6 | — | 1 | 4 | 2 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
Swell 3 Height (m) Direction Period (s) | W 10 | SW 6 | SW 11 | SW 11 | S 11 | — | — | — | — | — | — | — | — | — | W 7 | — | — | — | — | — | — |
| kJ | 2 | 1 | 4 | 5 | 2 | — | — | — | — | — | — | — | — | — | 1 | — | — | — | — | — | — |
Wind waves Height (m) Direction Period (s) | SSW 3 | — | SSW 5 | SSW 3 | SSW 2 | SW 4 | WNW 4 | NNW 4 | N 5 | NNW 5 | NNW 5 | N 5 | N 5 | N 5 | — | — | SW 3 | SW 5 | SW 6 | SW 6 | WSW 5 |
| kJ | 3 | — | 3 | 1 | 1 | 16 | 5 | 10 | 22 | 74 | 42 | 30 | 32 | 22 | — | — | 4 | 55 | 110 | 86 | 95 |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 235 | 163 | 163 | 187 | 249 | 192 | 179 | 179 | 332 | 318 | 589 | 251 | 251 | 286 | 280 | 275 | 298 | 51 | 114 | 251 | 251 |
Best forecast wave conditions in Anglesy | |||||||||||||||||||||
Best forecast wave conditions in United Kingdom | |||||||||||||||||||||
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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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