Surf Forecasts:
Guethary - Les Alcyons/Avalanche surf forecast from 21 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 (1.9m), 10s period, NW swell with 724 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 1.9m 10s and forecast to arrive on Friday (Aug 21) at 11AM. Winds are predicted to be cross-onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.4m 3s period and expected on Tuesday (Aug 25) at 8AM.
| 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 (1.9m) 10s |
Table - best surf conditions forecast for Guethary - Les Alcyons/Avalanche over the next 16 days.
The Lowdown
Alright folks, Rusty here. Let’s have a look at what’s coming up for the next couple of weeks.
The forecast opens with a bit of a flat start, but there’s a window of opportunity early on before a long quiet spell, then a promising pulse right at the end.
### Guethary - Les Alcyons/Avalanche
We’re looking at a classic reef break here, an expert-only wave that’s got a real reputation. The water temp is about what you’d expect for this time of year, nothing unusual to report.
The first real chance to get wet is Saturday, 22nd August. The Saturday morning session is the standout. We’ve got a clean 4ft NW swell with a period of 9 seconds, and a light easterly cross-offshore breeze making for some tidy, clean lines. The combined swell energy is a moderate 241, so there’s enough push to get into the waves. The afternoon goes a bit crumbly with a moderate cross-shore, so aim for the early.
We then hit a massive dry spell. From Sunday, 23rd August right through to Friday, 4th September, it’s pretty much a flat run. The swell drops out, and even when there’s a tiny bump, the conditions are poor. You’d be wasting your time. There’s a brief moment on Wednesday, 26th August with glassy conditions but the swell is barely 2ft. It’s just not enough.
Then, have a look at the end of the window. Saturday, 5th September, is the one to circle. The morning shows a clean 3ft NW swell (9 seconds) with a light cross-offshore breeze. The combined energy is a solid 238, so it’s got some life. This is promising, but it’s a long way out, so treat it as a hope, not a guarantee. For a break that’s often crowded, the early bird will get the cleanest ones.
So, to sum it up: Saturday, 22nd August morning is the best bet, and keep an eye on Saturday, 5th September morning as a potential late-game winner. The long gap in between is a real bummer, but that’s the way it goes sometimes.
Rusty.
Short Range ForecastHeavy rain (total 22mm), heaviest during Thu night. Warm (max 30°C on Sun afternoon, min 16°C on Sat morning). Wind will be generally light. | Days 5-7 Weather SummaryMostly dry. Warm (max 32°C on Mon afternoon, min 20°C on Sun night). Winds decreasing (fresh winds from the ESE on Mon afternoon, calm by Tue night). | ||||||||||||||||||
Friday 21 | Saturday 22 | Sunday 23 | Monday 24 | Tuesday 25 | Wednesday 26 | ||||||||||||||
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 10 | NW 10 | NW 10 | NW 10 | NW 9 | NW 9 | NW 8 | NW 7 | NW 7 | N 5 | N 5 | NW 6 | NNW 3 | NW 13 | NNW 12 | WNW 8 | WNW 8 | WNW 7 | WNW 9 |
Wave Graph  | |||||||||||||||||||
 kJ | 425 | 724 | 622 | 469 | 241 | 202 | 129 | 56 | 26 | 10 | 5 | 24 | 2 | 7 | 14 | 184 | 64 | 47 | 90 |
Wind (km/h) | |||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross-on | cross-on | cross-on | glassy | cross-off | cross | off | cross-off | cross-on | off | cross-off | off | cross-off | cross-off | cross-on | glassy | off | glassy | cross |
High Tide | 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 | 4:05PM3.21m | 4:26AM3.14m | 4:39PM3.45m | 4:59AM3.34m | ||||||
Low Tide | 5:08AM1.36m | 5:56PM1.38m | 6:31AM1.47m | 7:27PM1.38m | 7:56AM1.39m | 8:39PM1.22m | 8:57AM1.19m | 9:30PM0.99m | 9:43AM0.95m | 10:11PM0.74m | 10:20AM0.71m | 10:46PM0.50m | |||||||
 |  | |  |  | |  | | | | |  |  | | |  | |  | | |
 | — | 7:16 | — | — | 7:18 | — | — | 7:18 | — | — | 7:20 | — | — | 7:20 | — | — | 7:22 | — | — |
 | 9:01 | — | — | 9:00 | — | 8:59 | — | — | 8:58 | — | — | 8:55 | — | — | 8:53 | — | — | 8:52 | — |
mm | 6 | 6 | 4 | — | — | — | 6 | — | — | — | — | — | — | — | — | — | — | — | — |
Temp °C | 20 | 20 | 21 | 21 | 19 | 27 | 24 | 22 | 30 | 29 | 27 | 32 | 24 | 26 | 26 | 23 | 24 | 30 | 24 |
Feels °C | 20 | 19 | 19 | 21 | 17 | 25 | 25 | 24 | 29 | 29 | 28 | 31 | 25 | 25 | 25 | 24 | 25 | 30 | 24 |
Swell 1 Height (m) Direction Period (s) | NW 10 | — | NW 10 | NW 10 | NW 9 | NW 9 | NW 8 | NW 7 | NW 7 | N 5 | N 5 | — | NNW 3 | NW 6 | NNW 12 | WNW 8 | WNW 8 | WNW 7 | WNW 9 |
| kJ | 425 | — | 622 | 469 | 241 | 202 | 129 | 56 | 26 | 10 | 4 | — | 2 | 1 | 14 | 184 | 64 | 47 | 90 |
Swell 2 Height (m) Direction Period (s) | — | — | — | — | — | — | — | W 8 | W 8 | NW 7 | NNW 7 | — | N 5 | NW 13 | W 9 | NW 11 | NW 10 | NW 9 | — |
| kJ | — | — | — | — | — | — | — | 6 | 5 | 8 | 5 | — | 1 | 7 | 2 | 19 | 25 | 42 | — |
Swell 3 Height (m) Direction Period (s) | — | — | — | — | — | — | — | — | — | W 9 | W 9 | — | NW 6 | W 9 | W 8 | — | NW 12 | — | — |
| kJ | — | — | — | — | — | — | — | — | — | 7 | 2 | — | 2 | 2 | 1 | — | 6 | — | — |
Wind waves Height (m) Direction Period (s) | — | NW 10 | — | — | — | — | — | — | N 5 | — | — | NW 6 | — | SW 3 | NNW 4 | — | — | — | — |
| kJ | — | 724 | — | — | — | — | — | — | 9 | — | — | 24 | — | 1 | 5 | — | — | — | — |
Nearest Offshore or Glassy | |||||||||||||||||||
Distance (km) | 12 | 49 | 147 | 0 | 0 | 87 | 0 | 1 | 7 | 91 | 347 | 369 | 347 | 313 | 197 | 0 | 1 | 1 | 17 |
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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