Surf Forecasts:
Guethary - Les Alcyons/Avalanche surf forecast from 18 Aug 2026:
- Best quality surf: Friday 21 Aug, 11PM (local time) - 5ft (1.6m), 10s period, NW swell with glassy winds.
- Most powerful swell: Friday 21 Aug, 11AM (local time) - 6ft (1.8m), 10s period, NW swell with 634 kJ wave energy.
- Next surfable swell (1★+): Friday 21 Aug, 11PM (local time) - 5ft (1.6m), 10s period with NW 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 Friday (Aug 21) at 11PM. The primary swell is predicted to be 1.6m and 10s period. 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 1.8m 10s and forecast to arrive on Friday (Aug 21) at 11AM. Winds are predicted to be onshore at the time the swell arrives.
| Wave Type | Time (CEST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 11PM (Fri 21st Aug) | 5ft (1.6m) 10s |
| Best Surf | 11PM (Fri 21st Aug) | 5ft (1.6m) 10s |
| Most Powerful | 11AM (Fri 21st Aug) | 6ft (1.8m) 10s |
Table - best surf conditions forecast for Guethary - Les Alcyons/Avalanche over the next 16 days.
The Lowdown
Alright, Rusty here. Let’s talk about what’s happening over the next couple of weeks at Les-Alcyons-Avalanche.
Straight up, this is a spot for experts only. It’s a consistent reef break and it’s exposed to the west, which is where the best swell comes from. If you’re not dialled in, this isn’t the place. The water is sitting at 77°F, which is much warmer than normal for this time of year – a solid 6°F above average, so the old steamer can stay in the car.
Right now, there’s nothing doing. The first few days are flat and messy. It’s not until Thursday morning, August 20th, that we see a glimmer of life. That morning, we’ve got a 4ft NW groundswell with an 11-second period, and the wind is glassy from the WSW. The combined energy is moderate at 304, and it’s setting up for a clean, surfable bank. This is the first real look, but it’s not the standout.
The real highlight comes later. On Thursday morning, August 27th, things get serious. We’re looking at a 7ft NW groundswell with a 10-second period, and it’s glassy with a light SE wind – dead offshore for this break. The combined energy jumps to strong at 833. This is the best on offer: solid, clean, and powerful. At 7ft, we’re at the top end for experts, and the long period (10 seconds is solid) will give it proper shape and punch. Wind is perfect, conditions are glassy. This is the session you’d wait for. Bear in mind, the 27th is over a week away, so while it looks promising, keep an eye on it.
In between, there are a few mornings worth a look. Saturday the 22nd has clean, cross-off winds and 4ft NW swell (241 energy), and Sunday the 30th has glassy conditions with 4ft NW swell (249 energy). But the 27th is the clear winner.
After that, the surf fades back to small and choppy. The final row on September 2nd shows a 5ft NW swell but with onshore wind and messy conditions.
Overall, a slow start, one standout day if you’re patient, then a return to mush. For a reef this exposed, when it’s clean, it’s very good. When it’s not, don’t bother.
Rusty.
Short Range ForecastLight rain (total 8mm), mostly falling on Thu night. Warm (max 23°C on Wed afternoon, min 18°C on Wed morning). Wind will be generally light. | Days 5-7 Weather SummaryHeavy rain (total 30mm), heaviest during Mon afternoon. Warm (max 21°C on Fri night, min 16°C on Sat night). Wind will be generally light. | ||||||||||||||||||
Wednesday 19 | Thursday 20 | Friday 21 | Saturday 22 | Sunday 23 | Monday 24 | ||||||||||||||
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) | NW 7 | NW 6 | WNW 8 | NW 13 | NW 11 | NW 11 | NW 10 | NW 10 | NW 10 | NW 10 | NW 9 | NW 9 | NW 8 | NW 8 | NW 7 | NW 7 | NW 7 | NNW 6 | NW 6 |
Wave Graph  | |||||||||||||||||||
 kJ | 13 | 9 | 6 | 83 | 304 | 399 | 392 | 634 | 569 | 425 | 241 | 225 | 173 | 96 | 75 | 60 | 36 | 27 | 43 |
Wind (km/h) | |||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | glassy | on | on | cross-on | cross-on | cross-on | cross-on | on | on | glassy | glassy | cross-off | cross-off | cross-off | cross-on | cross-off | glassy | glassy | cross-on |
High Tide | 9:13PM3.21m | 9:33AM3.04m | 9:57PM2.89m | 10:21AM2.81m | 10:56PM2.63m | 11:31AM2.63m | 00:26AM2.48m | 1:09PM2.59m | 2:03AM2.54m | 2:31PM2.73m | 3:07AM2.71m | 3:24PM2.96m | 3:51AM2.93m | ||||||
Low Tide | 3:21AM0.82m | 3:43PM0.94m | 4:07AM1.12m | 4:39PM1.21m | 5:08AM1.36m | 5:56PM1.38m | 6:31AM1.47m | 7:27PM1.38m | 7:56AM1.39m | 8:39PM1.22m | 8:57AM1.19m | 9:30PM0.99m | |||||||
 | | |  |  | |  |  | |  | |  |  |  |  | | | |  | |
 | — | 7:15 | — | — | 7:16 | — | — | 7:16 | — | — | 7:18 | — | — | 7:18 | — | — | 7:20 | — | — |
 | 9:06 | — | — | 9:04 | — | — | 9:01 | — | — | 9:00 | — | 8:59 | — | — | 8:58 | — | — | 8:55 | — |
mm | — | — | — | — | — | — | 3 | 3 | 2 | — | 1 | — | 9 | 8 | 1 | — | 4 | 7 | 6 |
Temp °C | 22 | 21 | 23 | 22 | 22 | 22 | 20 | 20 | 21 | 21 | 19 | 19 | 18 | 16 | 18 | 18 | 16 | 17 | 19 |
Feels °C | 23 | 23 | 24 | 23 | 24 | 22 | 20 | 20 | 20 | 20 | 20 | 18 | 18 | 15 | 18 | 18 | 16 | 18 | 18 |
Swell 1 Height (m) Direction Period (s) | NW 7 | NW 6 | NNW 6 | NW 13 | NW 11 | NW 11 | NW 10 | NW 10 | NW 10 | NW 10 | NW 9 | NW 9 | NW 8 | NW 8 | NW 7 | NW 7 | NW 7 | NNW 6 | NW 6 |
| kJ | 13 | 9 | 3 | 83 | 304 | 399 | 392 | 634 | 569 | 425 | 241 | 225 | 173 | 96 | 75 | 60 | 36 | 27 | 43 |
Swell 2 Height (m) Direction Period (s) | NNW 5 | WNW 8 | WNW 8 | NW 7 | — | — | — | — | — | — | — | — | — | — | W 8 | — | — | W 8 | W 10 |
| kJ | 5 | 6 | 6 | 12 | — | — | — | — | — | — | — | — | — | — | 1 | — | — | 1 | 2 |
Swell 3 Height (m) Direction Period (s) | WNW 8 | — | NW 11 | WNW 7 | — | — | — | — | — | — | — | — | — | — | — | — | — | W 10 | — |
| kJ | 7 | — | 5 | 5 | — | — | — | — | — | — | — | — | — | — | — | — | — | 2 | — |
Wind waves Height (m) Direction Period (s) | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| kJ | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
Nearest Offshore or Glassy | |||||||||||||||||||
Distance (km) | 606 | 526 | 490 | 597 | 47 | 0 | 197 | 12 | 12 | 147 | 0 | 0 | 0 | 0 | 6 | 350 | 43 | 313 | 197 |
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.
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