Surf Forecasts:
Trearddur Bay (Holy Island) surf forecast from 15 Aug 2026:
- Most powerful swell: Thursday 20 Aug, 1AM (local time) - 3.5ft (1.1m), 5s period, SW swell with 55 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 1.1m 5s and forecast to arrive on Thursday (Aug 20) at 1AM. Winds are predicted to be cross-onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.8m 5s period and expected on Friday (Aug 21) at 7AM.
| Wave Type | Time (BST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | - | - |
| Best Surf | - | - |
| Most Powerful | 1AM (Thu 20th Aug) | 3.5ft (1.1m) 5s |
Table - best surf conditions forecast for Trearddur Bay (Holy Island) over the next 16 days.
Short Range ForecastLight rain (total 2mm), mostly falling on Mon night. Very mild (max 18°C on Mon night, min 14°C on Sat afternoon). Winds increasing (calm on Sat night, fresh winds from the S by Mon night). | Days 5-7 Weather SummaryLight rain (total 4mm), mostly falling on Wed night. Very mild (max 17°C on Tue afternoon, min 13°C on Thu night). Wind will be generally light. | |||||||||||||||||||
Sat 15 | Sunday 16 | Monday 17 | Tuesday 18 | Wednesday 19 | Thursday 20 | Friday 21 | ||||||||||||||
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 6 | SW 6 | — | — | SW 3 | SW 3 | SW 5 | SW 4 | SSW 5 | W 4 | W 4 | W 4 | SW 4 | SW 5 | SW 5 | SW 6 | SW 14 | WNW 4 | WNW 4 | SW 13 |
Wave Graph  | ||||||||||||||||||||
 kJ | 1 | 1 | 0 | 0 | 2 | 2 | 4 | 34 | 15 | 16 | 9 | 20 | 19 | 55 | 18 | 8 | 8 | 7 | 3 | 7 |
Wind (km/h) | ||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross-off | off | glassy | on | cross-on | cross-on | cross-on | on | cross | cross-on | cross | cross-on | cross-on | cross-on | cross | cross | cross-off | cross | cross-off | off |
High Tide | 1:10AM5.85m | 1:35PM5.37m | 1:49AM5.63m | 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 | ||||||||
Low Tide | 6:54PM0.71m | 7:25AM0.53m | 7:34PM0.87m | 8:05AM0.82m | 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 | |||||||
 |  |  |  |  | | |  | | | | | |  | | | | | | | |
 | — | — | 5:58 | — | — | 6:01 | — | — | 6:01 | — | — | 6:03 | — | — | 6:05 | — | — | 6:07 | — | — |
 | 8:46 | — | — | 8:45 | — | — | 8:43 | — | — | 8:40 | — | — | 8:37 | — | — | 8:36 | — | — | 8:34 | — |
mm | — | — | — | — | — | — | — | 2 | — | — | — | — | — | 4 | — | — | — | — | — | — |
Temp °C | 15 | 14 | 15 | 15 | 16 | 15 | 16 | 18 | 15 | 17 | 17 | 15 | 16 | 16 | 14 | 15 | 15 | 13 | 15 | 14 |
Feels °C | 12 | 11 | 15 | 12 | 15 | 13 | 13 | 16 | 11 | 13 | 13 | 10 | 11 | 13 | 11 | 13 | 14 | 10 | 12 | 9 |
Swell 1 Height (m) Direction Period (s) | SW 6 | N 3 | — | — | SW 4 | SW 3 | SW 5 | — | SSW 5 | — | — | SW 6 | NW 4 | SW 16 | SW 5 | SW 6 | SSW 5 | N 5 | WNW 4 | N 5 |
| kJ | 1 | 1 | — | — | 1 | 2 | 4 | — | 15 | — | — | 2 | 6 | 10 | 18 | 8 | 3 | 11 | 3 | 11 |
Swell 2 Height (m) Direction Period (s) | — | SW 6 | — | — | — | SW 5 | SW 5 | — | — | S 16 | W 17 | SW 16 | S 15 | — | SW 15 | SW 14 | SW 14 | SW 5 | NNW 4 | SW 13 |
| kJ | — | 1 | — | — | — | 1 | 4 | — | — | 5 | 6 | 10 | 5 | — | 8 | 8 | 8 | 1 | 3 | 7 |
Swell 3 Height (m) Direction Period (s) | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | SW 14 | SW 5 | — |
| kJ | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 7 | 1 | — |
Wind waves Height (m) Direction Period (s) | NNW 4 | — | — | — | SW 3 | NW 3 | NW 3 | SW 4 | NW 4 | W 4 | W 4 | W 4 | SW 4 | SW 5 | NW 4 | NNW 4 | N 4 | WNW 4 | — | NE 3 |
| kJ | 5 | — | — | — | 2 | 1 | 3 | 34 | 13 | 16 | 9 | 20 | 19 | 55 | 16 | 6 | 3 | 6 | — | 2 |
Nearest Offshore or Glassy | ||||||||||||||||||||
Distance (km) | 323 | 246 | 246 | 249 | 219 | 249 | 287 | 565 | 326 | 587 | 195 | 285 | 246 | 235 | 192 | 359 | 161 | 179 | 208 | 187 |
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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