Surf Forecasts:
Guethary - Les Alcyons/Avalanche surf forecast from 14 Sep 2026:
- Best quality surf: Friday 18 Sep, 11PM (local time) - 7.5ft (2.3m), 14s period, NW swell with glassy winds.
- Most powerful swell: Saturday 19 Sep, 2AM (local time) - 8ft (2.4m), 14s period, NW swell with 2,065 kJ wave energy.
- Next surfable swell (1★+): Monday 14 Sep, 8AM (local time) - 4.5ft (1.3m), 12s 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 Monday (Sep 14) at 8AM. The primary swell is predicted to be 1.3m and 12s period with a secondary swell of 0.3m and 4s. The wind is predicted to be offshore as the swell arrives.
The most powerful waves expected at Guethary - Les Alcyons/Avalanche in the next 16 days are 2.4m 14s and forecast to arrive on Saturday (Sep 19) at 2AM. Winds are predicted to be glassy at the time the swell arrives.
| Wave Type | Time (CEST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 8AM (Mon 14th Sep) | 4.5ft (1.3m) 12s |
| Best Surf | 11PM (Fri 18th Sep) | 7.5ft (2.3m) 14s |
| Most Powerful | 2AM (Sat 19th Sep) | 8ft (2.4m) 14s |
Table - best surf conditions forecast for Guethary - Les Alcyons/Avalanche over the next 16 days.
The Lowdown
Alright, Rusty here. Let’s break down what’s coming for Guethary – Les Alcyons/Avalanche. This is a reef wave that loves west swell and it’s strictly for experts. Don’t even think about it if you’re not dialed in.
The first few days are slow, but Monday morning the 14th brings a clean start. Swell is 4 ft from the NW with an 11-second period and moderate energy (414). Water temp is 73°, which is much warmer than usual for this time of year. Glassy conditions with an ENE wind at 3 mph. It’s a decent opener but not the main event.
Monday afternoon the wind shifts N at 6 mph, turning cross-onshore, and the quality slides. Swell drops to 4 ft. Tuesday and Wednesday look choppy and cross-onshore, with Tuesday morning only offering 3 ft and weak energy (144). Not worth the paddle.
Now, Thursday morning the 17th – glassy calm with a south-southeast breeze at 0 mph. Swell is 6 ft from the NW, 11-second period, energy climbing to 663. This is a clean, well-shaped window before the real juice arrives.
The big standout is Saturday morning the 19th. Swell is 7 ft from the NW with a long 13-second period and massive energy (1514). An east wind at 3 mph blowing cross-offshore means it’ll be clean and hollow. This is expert territory – 7 ft on a reef is serious. Crowds are likely, but this is the session you don’t miss.
Monday the 21st morning is another killer – 7 ft NW swell, 14-second period (very long period, so expect long waits between sets), and 1641 energy. Glassy with a northeast wind at 3 mph. Same deal: expert only, but firing.
After that, the swell slowly fades. Tuesday the 22nd morning is still clean with 5 ft and glassy wind. Friday the 25th brings a long-period 15-second WNW swell but cross-shore winds mess with the shape. Saturday the 26th morning cleans up again with a cross-offshore breeze and 5 ft NW swell – a decent end to the second week.
The last few days into the 28th and 29th get wrecked by strong cross-onshore winds and chop. Forget it.
Bottom line: Thursday 17th is a good early call, but Saturday 19th and Monday 21st are the standouts. Clean, powerful NW groundswell, offshore or glassy winds, and plenty of energy. Experts only, and expect company.
Rusty.
Short Range ForecastLight rain (total 3mm), mostly falling on Tue night. Warm (max 27°C on Mon afternoon, min 16°C on Wed night). Wind will be generally light. | Days 4-6 Weather SummaryLight rain (total 5mm), mostly falling on Fri morning. Warm (max 21°C on Sat afternoon, min 15°C on Fri night). Wind will be generally light. | ||||||||||||||||||||
Monday 14 | Tuesday 15 | Wednesday 16 | Thursday 17 | Friday 18 | Saturday 19 | Sunday 20 | |||||||||||||||
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) | NW 11 | NW 11 | NW 10 | NW 10 | NW 9 | NW 9 | WNW 10 | NW 9 | NW 10 | NW 11 | NW 11 | NW 10 | NW 10 | NW 9 | NW 14 | NW 13 | NW 13 | NW 12 | NW 12 | NW 11 | NW 10 |
Wave Graph  | |||||||||||||||||||||
 kJ | 411 | 286 | 212 | 133 | 55 | 48 | 127 | 402 | 416 | 663 | 548 | 315 | 204 | 332 | 2065 | 1514 | 1279 | 736 | 573 | 457 | 424 |
Wind (km/h) | |||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | glassy | cross-on | cross-off | cross-on | cross-on | on | cross-on | on | cross | glassy | on | cross-on | cross-on | on | glassy | cross-off | cross-on | glassy | cross-off | cross-on | cross |
High Tide | 7:21PM3.72m | 7:37AM3.56m | 7:55PM3.45m | 8:09AM3.34m | 8:29PM3.14m | 8:44AM3.08m | 9:09PM2.84m | 9:27AM2.82m | 10:03PM2.57m | 10:34AM2.60m | 11:37PM2.40m | 12:24PM2.53m | 1:30AM2.46m | ||||||||
Low Tide | 1:05PM0.15m | 1:25AM0.30m | 1:41PM0.37m | 1:59AM0.57m | 2:19PM0.65m | 2:36AM0.87m | 3:01PM0.94m | 3:18AM1.17m | 3:54PM1.23m | 4:17AM1.42m | 5:12PM1.43m | 5:47AM1.55m | 6:54PM1.44m | ||||||||
 | |  | | |  |  |  | |  |  |  | | | | | | | | | | |
 | 7:43 | — | — | 7:45 | — | — | 7:46 | — | — | 7:47 | — | — | 7:48 | — | — | 7:48 | — | — | 7:50 | — | — |
 | — | 8:19 | — | — | 8:16 | — | — | 8:15 | — | — | 8:14 | — | — | 8:12 | — | — | 8:09 | — | — | 8:07 | — |
mm | — | — | — | — | — | 1 | 1 | — | 1 | — | 1 | — | 4 | — | — | — | — | — | — | — | — |
Temp °C | 22 | 27 | 24 | 22 | 22 | 21 | 19 | 19 | 19 | 17 | 19 | 19 | 17 | 19 | 18 | 17 | 21 | 19 | 19 | 25 | 21 |
Feels °C | 20 | 25 | 25 | 21 | 21 | 21 | 19 | 17 | 18 | 18 | 17 | 17 | 15 | 18 | 17 | 17 | 19 | 19 | 18 | 23 | 22 |
Swell 1 Height (m) Direction Period (s) | NW 11 | NW 11 | NW 10 | NW 10 | NW 9 | WNW 4 | NW 6 | NW 9 | NW 10 | NW 11 | NW 11 | NW 10 | NW 10 | NW 9 | NW 14 | NW 13 | NW 13 | NW 12 | NW 12 | NW 11 | NW 10 |
| kJ | 411 | 286 | 212 | 133 | 55 | 13 | 94 | 402 | 416 | 663 | 548 | 315 | 204 | 332 | 2065 | 1514 | 1279 | 736 | 573 | 457 | 424 |
Swell 2 Height (m) Direction Period (s) | N 4 | N 4 | — | W 9 | WNW 9 | NW 9 | WNW 10 | — | NW 12 | — | — | — | NW 12 | NW 15 | — | — | — | — | — | W 19 | NW 16 |
| kJ | 3 | 1 | — | 7 | 15 | 38 | 127 | — | 244 | — | — | — | 6 | 224 | — | — | — | — | — | 7 | 163 |
Swell 3 Height (m) Direction Period (s) | — | — | — | W 13 | WNW 12 | WNW 11 | — | — | — | — | — | — | NW 16 | — | — | — | — | — | — | — | — |
| kJ | — | — | — | 4 | 15 | 48 | — | — | — | — | — | — | 11 | — | — | — | — | — | — | — | — |
Wind waves Height (m) Direction Period (s) | — | — | — | — | WNW 4 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| kJ | — | — | — | — | 17 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 0 | 11 | 0 | 12 | 597 | 87 | 87 | 147 | 6 | 0 | 12 | 12 | 9 | 87 | 0 | 0 | 87 | 0 | 0 | 87 | 6 |
Best forecast wave conditions in La Cote Basque | |||||||||||||||||||||
Best forecast wave conditions in France | |||||||||||||||||||||
Header Global | |||||||||||||||||||||
- Map Icons:
Break
Live Wave Height (m)
Live Wind Speed (km/h)
Surf Rating (10 Max)
Ocean Swells (m)- Wind Speed (km/h)
FREE! Surf-Forecast.com widget for your website
The surf report / weather widget below is available to embed on third party websites free of charge and provides a summary of our Guethary - Les Alcyons/Avalanche surf forecast. Simply grab the html code snippet that we provide and paste it into your own site. You can choose your preferred language and metric/imperial units for the surf forecast feed to suit users of your site. Click here to get the code.
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.
Nearest