Surf Forecasts:
Guethary - Les Alcyons/Avalanche surf forecast from 25 Aug 2026:
- Best quality surf: Saturday 29 Aug, 5AM (local time) - 6.5ft (2.0m), 10s period, WNW swell with cross-offshore winds.
- Most powerful swell: Friday 28 Aug, 11PM (local time) - 7.5ft (2.3m), 10s period, WNW swell with 1,045 kJ wave energy.
- Next surfable swell (1★+): Thursday 27 Aug, 8PM (local time) - 3ft (0.9m), 8s period with WNW swell.
Best Forecast Surf Conditions for Guethary - Les Alcyons/Avalanche this week:
The surf forecast for Guethary - Les Alcyons/Avalanche over the next 16 days: The first swell (rated 1 star or higher) is forecast to arrive on Thursday (Aug 27) at 8PM. The primary swell is predicted to be 0.9m and 8s period with a secondary swell of 0.1m and 12s. The wind is predicted to be glassy as the swell arrives.
The most powerful waves expected at Guethary - Les Alcyons/Avalanche in the next 16 days are 2.3m 10s and forecast to arrive on Friday (Aug 28) at 11PM. Winds are predicted to be cross-onshore at the time the swell arrives.
| Wave Type | Time (CEST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 8PM (Thu 27th Aug) | 3ft (0.9m) 8s |
| Best Surf | 5AM (Sat 29th Aug) | 6.5ft (2.0m) 10s |
| Most Powerful | 11PM (Fri 28th Aug) | 7.5ft (2.3m) 10s |
Table - best surf conditions forecast for Guethary - Les Alcyons/Avalanche over the next 16 days.
The Lowdown
Alright folks, Rusty here, looking at the local scene. We’ve got one spot on the radar for the next couple of weeks, and it’s a ripper of a reef setup that’s only for the brave. It’s going to be a bit of a waiting game for the real magic, but when it comes, it’ll be worth the wait.
For the next week or so, honestly, don’t get wet. From now through the end of August, the swell is tiny and the conditions are messy. We’re looking at weak, short-period junk in the 1 to 2 ft range with mostly onshore or cross-onshore winds. The energy levels are pathetic, barely breaking triple digits (25 to 61). A few mornings might look clean or glassy, but there’s just no power behind it. The swell is poor, so give the boards a rest.
We start to see a pulse of energy pick up around the 28th of August. Friday morning the swell jumps to 6 ft, but it’s coming with a stiff cross-shore and a combined energy of 365, which is moderate but not clean. The wind is all over the place, so while it’s bigger, the quality isn’t there yet.
Now, here’s where it gets interesting. The standout session looks to be Saturday the 29th, first light. We’ve got a 5 ft NW groundswell with a clean 9-second period, and the wind is a light easterly, giving us a clean, cross-offshore flow. The energy is pumping at 388, and for a reef this exposed, that’s solid. This is the best on offer in the early window – it’s the one to aim for. Expect a buttery morning with decent, powerful waves. Later that afternoon the wind swings north and messes it up, so it’s a morning-only strike.
There’s another big gap of poor conditions after that until the 1st of September. Tuesday the 1st of September morning is looking very promising. We’ve got a sweet 6 ft NW groundswell, a 10-second period, and clean cross-offshore easterly winds. The combined energy is cranking at 628, making for some moderate to strong wave energy. This is a solid, proper groundswell for the point.
The real beast, though, is sitting out there for the 8th of September. That Tuesday morning is showing a massive 13 ft WNW swell with a 10-second period and glassy conditions. The combined energy is an insane 3476, which is very strong. This is a big, powerful swell, and for a reef like this, only experts should even think about it. It will be huge, clean, and dangerous. The confidence is lower this far out, but if it comes together, it will be the wave of the month. The following Wednesday the 9th still has solid 6 ft energy but the wind is more onshore and messy.
This spot is a consistent, expert-only reef break. It’s exposed to the west and the optimum swell is from the west, so that big WNW swell is dead on. Be warned, it gets *often* crowded, so for the best sessions, you’ll be in a pack. Also, the water is unusually warm right now; the anomaly is 3°C above normal, so it’s much warmer than usual for late August.
For the kite surfers among ya, watch the afternoons. When that swell is over 5 ft with strong cross-onshore winds, like 28th August afternoon, it’s going to be more fun on a kite than a paddle board.
All in all, wait for Saturday the 29th morning, then mark your calendar for the 1st and 8th of September.
Cheers,
Rusty
Short Range ForecastSome drizzle, heaviest during Tue morning. Warm (max 33°C on Wed afternoon, min 19°C on Tue night). Wind will be generally light. | Days 4-6 Weather SummaryMostly dry. Warm (max 23°C on Fri afternoon, min 17°C on Sat morning). Wind will be generally light. | ||||||||||||||||||||
Tuesday 25 | Wednesday 26 | Thursday 27 | Friday 28 | Saturday 29 | Sunday 30 | Monday 31 | |||||||||||||||
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) | WNW 4 | NW 12 | NW 11 | NW 10 | NW 10 | WNW 9 | NW 8 | WNW 8 | WNW 8 | WNW 8 | WNW 9 | WNW 10 | NW 9 | NW 9 | NW 8 | WNW 8 | WNW 8 | NW 8 | WNW 8 | NW 10 | NW 10 |
Wave Graph | |||||||||||||||||||||
15 | 23 | 31 | 26 | 29 | 31 | 17 | 58 | 92 | 365 | 475 | 951 | 388 | 281 | 222 | 235 | 235 | 78 | 103 | 355 | 527 | |
Wind (km/h) | |||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross-on | on | glassy | cross-off | cross-off | cross-on | glassy | cross-on | cross | cross | on | cross | cross-off | cross-on | glassy | cross-on | on | cross | on | on | off |
High Tide | 4:05PM3.21m | 4:26AM3.14m | 4:39PM3.45m | 4:59AM3.34m | 5:10PM3.65m | 5:29AM3.50m | 5:41PM3.80m | 6:00AM3.62m | 6:13PM3.88m | 6:31AM3.68m | 6:45PM3.89m | 7:04AM3.68m | 7:19PM3.81m | ||||||||
Low Tide | 9:43AM0.95m | 10:11PM0.74m | 10:20AM0.71m | 10:46PM0.50m | 10:54AM0.49m | 11:18PM0.31m | 11:26AM0.32m | 11:50PM0.17m | 11:59AM0.21m | 00:22AM0.10m | 12:31PM0.16m | 00:54AM0.10m | 1:06PM0.19m | 1:28AM0.19m | |||||||
7:20 | — | — | 7:22 | — | — | 7:24 | — | — | 7:24 | — | — | 7:26 | — | — | 7:26 | — | — | 7:28 | — | — | |
— | 8:53 | — | — | 8:52 | — | — | 8:51 | — | — | 8:49 | — | — | 8:47 | — | — | 8:45 | — | — | 8:44 | — | |
mm | 1 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 1 | 1 | — |
Temp °C | 23 | 24 | 22 | 23 | 33 | 28 | 22 | 24 | 22 | 21 | 23 | 21 | 20 | 23 | 21 | 21 | 22 | 21 | 21 | 21 | 20 |
Feels °C | 23 | 24 | 24 | 24 | 31 | 27 | 23 | 24 | 23 | 17 | 19 | 20 | 20 | 22 | 21 | 22 | 22 | 21 | 22 | 21 | 20 |
Swell 1 Height (m) Direction Period (s) | NW 13 | WNW 4 | WNW 5 | NW 10 | WNW 7 | WNW 7 | WNW 6 | WNW 8 | WNW 8 | WNW 8 | WNW 9 | WNW 10 | NW 9 | NW 9 | NW 8 | WNW 8 | WNW 8 | NW 8 | WNW 8 | NW 10 | NW 10 |
7 | 11 | 11 | 26 | 29 | 17 | 12 | 58 | 92 | 365 | 475 | 951 | 388 | 281 | 222 | 235 | 235 | 78 | 103 | 355 | 527 | |
Swell 2 Height (m) Direction Period (s) | NW 9 | NW 12 | NW 11 | NW 5 | NW 10 | WNW 9 | NW 8 | — | NW 11 | — | — | — | — | — | — | — | — | WNW 8 | NW 10 | — | — |
3 | 23 | 31 | 7 | 24 | 31 | 17 | — | 5 | — | — | — | — | — | — | — | — | 60 | 26 | — | — | |
Swell 3 Height (m) Direction Period (s) | — | W 8 | W 8 | WNW 7 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
— | 1 | 1 | 5 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | |
Wind waves Height (m) Direction Period (s) | WNW 4 | — | — | — | — | — | — | NNW 3 | SW 3 | — | — | — | — | — | — | — | — | — | — | — | — |
15 | — | — | — | — | — | — | 3 | 5 | — | — | — | — | — | — | — | — | — | — | — | — | |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 387 | 197 | 1 | 31 | 1 | 47 | 162 | 2 | 17 | 12 | 436 | 6 | 0 | 87 | 0 | 11 | 87 | 12 | 147 | 87 | 0 |
Best forecast wave conditions in La Cote Basque | |||||||||||||||||||||
Best forecast wave conditions in France | |||||||||||||||||||||
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Information about the Guethary - Les Alcyons/Avalanche Surf forecast
The above surf forecast table for Guethary - Les Alcyons/Avalanche provides essential information for determining whether the surfing conditions will be good over the next 16 days. A general guide to surfing at Guethary - Les Alcyons/Avalanche can be found by selecting the local surf guide option on the grey menu. Our Guethary - Les Alcyons/Avalanche 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 (Guethary - Les Alcyons/Avalanche) 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 Guethary - Les Alcyons/Avalanche 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.
Guethary - Les Alcyons/Avalanche is 9 km (6 miles) from Biarritz. If you plan a holiday in La Cote Basque, look for hotels and other accommodation in Biarritz. Biarritz has rooms for a wide range of budgets as well as car hire and transport links.











