Surf Forecasts:
Trearddur Bay (Holy Island) surf forecast from 17 Aug 2026:
- Most powerful swell: Wednesday 19 Aug, 10PM (local time) - 4.5ft (1.3m), 6s period, SW swell with 124 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 1.3m 6s and forecast to arrive on Wednesday (Aug 19) at 10PM. Winds are predicted to be cross-onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 1.0m 5s period and expected on Sunday (Aug 23) at 7AM.
| Wave Type | Time (BST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | - | - |
| Best Surf | - | - |
| Most Powerful | 10PM (Wed 19th Aug) | 4.5ft (1.3m) 6s |
Table - best surf conditions forecast for Trearddur Bay (Holy Island) over the next 16 days.
The Lowdown
Alright folks, Rusty here. Let’s take a look at what’s shaping up for Trearddur Bay (Holy Island).
To be straight with you, the next week and a half is a bit of a write-off. We’re looking at a long dry spell starting from Monday the 17th of August, stretching all the way through to the 26th. For days on end, there’s just nothing to get excited about – tiny swell, poor conditions, and consistent "poor surf" flags. It’s the kind of stretch where you’re better off finding something else to do.
The water temperature is sitting at 63°, which is a touch warmer than usual for this time of year, so at least a dip won't be a shock, but that’s about the only positive.
Towards the end of the month, we finally see a pulse of energy. Thursday the 27th of August brings a bit of a lift, with a 3ft swell from the SSW, but the wind is cross and messy. The real change comes Thursday afternoon: a jump in swell to 6ft from the SSW, with a period of 6 seconds and a combined energy of 246. That’s moderate wave energy, but it’s accompanied by strong onshore winds, so it’s going to be a messy, blown-out mess. Not for the faint-hearted.
The standouts, if you can call them that, arrive on Sunday the 30th of August. We’ve got a 7ft swell from the SSW on Sunday afternoon, with a combined energy of 359. That’s a solid amount of power, but the wind is onshore at 22 mph, making it rough and raw. This is expert-only territory, and even then, it’s going to be a battle. The swell is short period, around 6 seconds, so it’s not going to be the cleanest shape.
Monday the 31st of August keeps the size up, with 6ft from the SW and energy of 282, but again, the wind is onshore or cross-onshore. It’s powerful, sure, but it’s also messy. The best call for the whole run? Honestly, it’s a tough one. The breaks here are inconsistent at the best of times, and with the wind being so against us, there’s no clean, glassy session in the cards. If you’ve got a tow-in board and a death wish, Sunday afternoon might be your moment. For everyone else, you’re waiting for a better day.
Rusty.
Short Range ForecastLight rain (total 7mm), mostly falling on Mon night. Very mild (max 18°C on Mon night, min 14°C on Tue night). Mainly fresh winds. | Days 4-6 Weather SummaryLight rain (total 6mm), mostly falling on Thu night. Very mild (max 15°C on Thu morning, min 13°C on Thu night). Mainly fresh winds. | ||||||||||||||||||||
Monday 17 | Tuesday 18 | Wednesday 19 | Thursday 20 | Friday 21 | Saturday 22 | Sunday 23 | |||||||||||||||
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 5 | SW 5 | SW 4 | WSW 4 | SW 6 | WSW 4 | SW 5 | SW 5 | WSW 6 | SW 6 | SW 6 | SW 14 | SW 14 | W 3 | SW 13 | SW 15 | SW 15 | SW 15 | SW 14 | SW 14 | SW 14 |
Wave Graph  | |||||||||||||||||||||
 kJ | 6 | 4 | 22 | 31 | 17 | 24 | 49 | 63 | 108 | 23 | 10 | 8 | 7 | 1 | 7 | 8 | 8 | 8 | 8 | 7 | 8 |
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 | on | on | cross-on | cross-off | cross-off | cross-off | cross | off | off | cross-off | cross-off | cross-off | cross-off | cross-off | off |
High Tide | 2:12PM5.16m | 2:28AM5.33m | 2:51PM4.93m | 3:07AM4.98m | 3:32PM4.68m | 3:52AM4.62m | 4:23PM4.44m | 4:52AM4.29m | 5:32PM4.26m | 6:23AM4.10m | 7:07PM4.27m | 8:04AM4.17m | 8:27PM4.49m | ||||||||
Low Tide | 8:13PM1.14m | 8:44AM1.19m | 8:54PM1.47m | 9:26AM1.59m | 9:39PM1.83m | 10:14AM1.98m | 10:37PM2.18m | 11:17AM2.31m | 11:58PM2.41m | 12:45PM2.45m | 1:37AM2.37m | 2:08PM2.34m | 2:47AM2.11m | ||||||||
 | |  | | |  |  |  |  | |  | |  | | | | | | | | | |
 | 6:01 | — | — | 6:01 | — | — | 6:03 | — | — | 6:05 | — | — | 6:07 | — | — | 6:09 | — | — | 6:11 | — | — |
 | — | 8:43 | — | — | 8:40 | — | — | 8:37 | — | — | 8:36 | — | — | 8:34 | — | — | 8:31 | — | — | 8:29 | — |
mm | — | — | 2 | — | — | — | — | 2 | 3 | — | — | 1 | 2 | 1 | 2 | — | — | — | — | — | — |
Temp °C | 16 | 16 | 18 | 16 | 18 | 17 | 16 | 17 | 16 | 15 | 15 | 14 | 15 | 15 | 14 | 14 | 15 | 15 | 14 | 15 | 15 |
Feels °C | 16 | 15 | 16 | 12 | 15 | 12 | 10 | 14 | 13 | 10 | 9 | 11 | 13 | 12 | 10 | 9 | 10 | 12 | 10 | 11 | 12 |
Swell 1 Height (m) Direction Period (s) | SW 5 | SW 5 | — | — | NW 4 | — | NW 5 | S 15 | SW 16 | SW 6 | SW 6 | SSW 6 | SW 5 | NNW 4 | SW 13 | NNW 4 | SW 15 | SW 15 | SW 14 | SW 14 | NNW 4 |
| kJ | 6 | 4 | — | — | 8 | — | 1 | 5 | 10 | 23 | 10 | 3 | 1 | 6 | 7 | 3 | 8 | 8 | 8 | 7 | 3 |
Swell 2 Height (m) Direction Period (s) | — | NW 3 | — | — | — | — | SW 16 | — | — | SW 15 | SW 14 | SW 14 | SW 14 | W 3 | — | SW 15 | — | S 12 | — | — | SW 14 |
| kJ | — | 2 | — | — | — | — | 10 | — | — | 8 | 8 | 8 | 7 | 1 | — | 8 | — | 3 | — | — | 8 |
Swell 3 Height (m) Direction Period (s) | — | — | — | — | — | — | — | — | — | — | — | — | SW 13 | SW 5 | — | — | — | — | — | — | — |
| kJ | — | — | — | — | — | — | — | — | — | — | — | — | 7 | 1 | — | — | — | — | — | — | — |
Wind waves Height (m) Direction Period (s) | NW 3 | WNW 3 | SW 4 | WSW 4 | SW 6 | WSW 4 | SW 5 | SW 5 | WSW 6 | NNW 4 | N 5 | N 4 | NNW 4 | NW 4 | NNE 4 | NE 4 | NNW 3 | N 4 | NNW 5 | N 4 | — |
| kJ | 3 | 2 | 22 | 31 | 17 | 24 | 49 | 63 | 108 | 31 | 22 | 12 | 17 | 8 | 7 | 1 | 2 | 10 | 35 | 15 | — |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 249 | 287 | 567 | 51 | 514 | 251 | 251 | 235 | 288 | 179 | 219 | 179 | 179 | 284 | 163 | 163 | 241 | 273 | 273 | 330 | 267 |
Best forecast wave conditions in Anglesy | |||||||||||||||||||||
Best forecast wave conditions in United Kingdom | |||||||||||||||||||||
Header Global | |||||||||||||||||||||
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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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