Surf Forecasts:
Trearddur Bay (Holy Island) surf forecast from 12 Sep 2026:
- Best quality surf: Sunday 13 Sep, 1AM (local time) - 3.5ft (1.0m), 7s period, SW swell with glassy winds.
- Most powerful swell: Saturday 12 Sep, 4PM (local time) - 6ft (1.9m), 7s period, SW swell with 355 kJ wave energy.
- Next surfable swell (1★+): Sunday 13 Sep, 1AM (local time) - 3.5ft (1.0m), 7s period with SW swell.
Best Forecast Surf Conditions for Trearddur Bay (Holy Island) this week:
The surf forecast for Trearddur Bay (Holy Island) over the next 16 days: The first swell (rated 1 star or higher) is forecast to arrive on Sunday (Sep 13) at 1AM. The primary swell is predicted to be 1.0m and 7s period with a secondary swell of 0.3m and 4s. The wind is predicted to be glassy as the swell arrives.
The most powerful waves expected at Trearddur Bay (Holy Island) in the next 16 days are 1.9m 7s and forecast to arrive on Saturday (Sep 12) at 4PM. Winds are predicted to be onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 1.6m 6s period and expected on Wednesday (Sep 16) at 4AM.
| Wave Type | Time (BST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 1AM (Sun 13th Sep) | 3.5ft (1.0m) 7s |
| Best Surf | 1AM (Sun 13th Sep) | 3.5ft (1.0m) 7s |
| Most Powerful | 4PM (Sat 12th Sep) | 6ft (1.9m) 7s |
Table - best surf conditions forecast for Trearddur Bay (Holy Island) over the next 16 days.
The Lowdown
Alright, surfers, Rusty here with a look at what's coming up for Trearddur Bay. Gotta be straight with you, this outlook is a tough one. We're looking at a long, long stretch of poor surf conditions right through until the end of the 16-day window. There's a massive gap of nothing worthwhile on offer.
We'll kick off with Saturday the 12th. The water's a touch warmer than normal for this time of year, sitting at 62°F, but that's the only good news. We've got a strong 8ft swell from the southwest, but it's onshore and blowing a gale at 28 mph. There's some moderate-strong wave energy in the water (505), but with those winds, it's just a washing machine. Not a chance. That afternoon is barely any better with a 6ft swell and 22 mph onshore wind.
Sunday the 13th morning might be the only window that looks half-decent all week. The wind swings offshore from the ENE at a slight 3 mph, which would leave it glassy clean. Problem is, the swell drops right off to a tiny 2ft from the south-southwest, with next to no energy (26). It's a beginner-friendly, inconsistent spot at the best of times, so unless you're on a foamie and just want some clean, tiny bumps, there's nothing to get excited about.
The rest of the first week and into the second is a write-off. Monday the 14th and Tuesday the 15th see messy onshore winds and lumpy conditions. By Wednesday the 16th, the swell flatlines. We get another spike of bigger swell on Sunday the 20th, with an 8ft southwest swell and a period of 8 seconds, but with a near-gale onshore wind at 31 mph, those waves will be blown-out and dangerous. Over 8ft in those conditions is strictly for the nutters or the kite surfers.
Monday the 21st morning offers a brief moment of calm with glassy conditions and a tiny 2ft swell, but again, no power behind it (60). After that, it's back to tiny, weak waves and cross-onshore wind patterns all the way through to the 27th. Even the offshore winds on Friday the 25th only manage 1ft waves with a 4-second period. It's just flat, clean, and boring.
Honestly, there's no standout day here. The whole 16 days is a blank run with barely a ripple worth paddling for. Keep the board in the car and maybe find a lake, because the ocean’s not giving us anything.
Rusty.
Short Range ForecastModerate rain (total 13mm), heaviest on Sat morning. Very mild (max 18°C on Sat afternoon, min 14°C on Mon night). Winds decreasing (strong winds from the SW on Sat morning, calm by Sat night). | Days 4-6 Weather SummarySome drizzle, heaviest during Wed night. Very mild (max 16°C on Tue afternoon, min 12°C on Wed morning). Mainly fresh winds. | ||||||||||||||||||||
Saturday 12 | Sunday 13 | Monday 14 | Tuesday 15 | Wednesday 16 | Thursday 17 | Friday 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 7 | SW 7 | SW 7 | SSW 6 | SSW 6 | SSW 3 | SSW 5 | SSW 6 | SSW 6 | SW 6 | SW 6 | SW 6 | S 11 | W 4 | WSW 4 | W 5 | W 5 | W 5 | WSW 4 | SW 5 | SW 6 |
Wave Graph  | |||||||||||||||||||||
 kJ | 505 | 355 | 91 | 26 | 14 | 10 | 45 | 160 | 196 | 80 | 19 | 5 | 2 | 11 | 37 | 104 | 55 | 50 | 30 | 66 | 156 |
Wind (km/h) | |||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | on | on | glassy | off | on | cross-on | on | cross-on | on | cross-on | cross | cross | cross | cross-on | on | cross-on | cross-on | cross-on | cross-on | on | on |
High Tide | 11:50AM5.61m | 00:04AM5.91m | 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 | ||||||||
Low Tide | 5:49PM0.68m | 6:16AM0.50m | 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 | ||||||||
 |  |  | | | | |  |  | |  | | |  | | | | | | | | |
 | 6:45 | — | — | 6:47 | — | — | 6:48 | — | — | 6:50 | — | — | 6:52 | — | — | 6:54 | — | — | 6:56 | — | — |
 | — | 7:42 | — | — | 7:39 | — | — | 7:37 | — | — | 7:35 | — | — | 7:32 | — | — | 7:30 | — | — | 7:28 | — |
mm | 7 | — | — | — | — | — | — | 3 | 3 | — | — | — | — | — | 1 | — | — | — | — | — | — |
Temp °C | 16 | 18 | 18 | 17 | 17 | 17 | 17 | 17 | 17 | 14 | 16 | 14 | 13 | 15 | 15 | 14 | 15 | 14 | 14 | 15 | 16 |
Feels °C | 9 | 15 | 17 | 17 | 17 | 15 | 14 | 11 | 12 | 10 | 12 | 8 | 9 | 10 | 10 | 7 | 9 | 7 | 9 | 10 | 10 |
Swell 1 Height (m) Direction Period (s) | — | — | SW 7 | SSW 6 | SSW 6 | — | — | — | — | SW 6 | SW 6 | SW 6 | SW 5 | NNW 5 | NNW 4 | — | — | — | — | — | — |
| kJ | — | — | 91 | 26 | 14 | — | — | — | — | 80 | 16 | 5 | 1 | 27 | 2 | — | — | — | — | — | — |
Swell 2 Height (m) Direction Period (s) | — | — | NW 4 | N 4 | — | — | — | — | — | — | — | — | S 11 | — | — | — | — | — | — | — | — |
| kJ | — | — | 2 | 1 | — | — | — | — | — | — | — | — | 2 | — | — | — | — | — | — | — | — |
Swell 3 Height (m) Direction Period (s) | — | — | — | — | — | — | — | — | — | — | — | — | — | W 11 | — | — | — | — | — | — | — |
| kJ | — | — | — | — | — | — | — | — | — | — | — | — | — | 2 | — | — | — | — | — | — | — |
Wind waves Height (m) Direction Period (s) | SW 7 | SW 7 | — | NNE 4 | — | SSW 3 | SSW 5 | SSW 6 | SSW 6 | WNW 4 | NW 4 | NW 5 | NW 6 | W 4 | WSW 4 | W 5 | W 5 | W 5 | WSW 4 | SW 5 | SW 6 |
| kJ | 505 | 355 | — | 3 | — | 10 | 45 | 160 | 196 | 34 | 19 | 129 | 97 | 11 | 37 | 104 | 55 | 50 | 30 | 66 | 156 |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 251 | 323 | 0 | 179 | 187 | 246 | 246 | 278 | 251 | 179 | 192 | 192 | 192 | 235 | 280 | 293 | 548 | 299 | 251 | 251 | 246 |
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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