Surf Forecasts:
Guethary - Les Alcyons/Avalanche surf forecast from 9 Sep 2026:
- Best quality surf: Sunday 13 Sep, 11AM (local time) - 4.5ft (1.3m), 13s period, NW swell with glassy winds.
- Most powerful swell: Sunday 13 Sep, 5PM (local time) - 5ft (1.5m), 12s period, NW swell with 645 kJ wave energy.
- Next surfable swell (1★+): Thursday 10 Sep, 2AM (local time) - 5ft (1.5m), 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 Thursday (Sep 10) at 2AM. The primary swell is predicted to be 1.5m 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 1.5m 12s and forecast to arrive on Sunday (Sep 13) at 5PM. 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+) | 2AM (Thu 10th Sep) | 5ft (1.5m) 10s |
| Best Surf | 11AM (Sun 13th Sep) | 4.5ft (1.3m) 13s |
| Most Powerful | 5PM (Sun 13th Sep) | 5ft (1.5m) 12s |
Table - best surf conditions forecast for Guethary - Les Alcyons/Avalanche over the next 16 days.
The Lowdown
Alright, Rusty here. Let’s talk about Guethary – Les Alcyons/Avalanche.
This is an expert-level reef break, and looking at the next sixteen days, things start slow before getting real good. The water is sitting at 74° which is much warmer than usual for this time of year—a nice little bonus.
The first few days aren’t worth the walk. Wednesday the 9th is messy with a 5ft NW swell and cross-on wind. Thursday the 10th morning cleans up with light easterly breeze and a dropping 4ft NW swell, but nothing special. Friday through Saturday are tiny and weak.
The real standout is Sunday, September 13th. That morning is the one. We’ve got a 4ft NW groundswell with a long 13-second period and glassy conditions. The combined energy is a solid 609 – moderate to strong. That long period means power and shape. For an expert reef, this is prime. Clean, lined-up sets with decent lulls.
The following week stays consistent with waist-to-chest high NW swell, mostly 4ft to 4ft, and plenty of clean windows. Monday the 14th morning and Saturday the 19th morning both look fun with light offshore or glassy conditions. Then we’ve got Monday, September 22nd which is another standout: Tuesday morning the 22nd is glassy with a 4ft NW swell, very long 12-second period, and combined energy of 885. That’s a proper groundswell hitting the reef with no wind – a special morning for the experts.
Also worth a note: September 21st sees a jump in size to a solid 10ft NW swell, but that’s for experts only. The wind is onshore or cross-onshore, so it’ll be lumpy and heavy. Marginal but heavy.
Crowds are *often* here, and with this quality, expect company on those standout mornings.
Rusty.
Short Range ForecastSome drizzle, heaviest during Wed afternoon. Warm (max 20°C on Fri afternoon, min 15°C on Thu morning). Wind will be generally light. | Days 5-7 Weather SummaryMostly dry. Warm (max 26°C on Mon afternoon, min 17°C on Sat night). Wind will be generally light. | |||||||||||||||||||
Wed 9 | Thursday 10 | Friday 11 | Saturday 12 | Sunday 13 | Monday 14 | Tuesday 15 | ||||||||||||||
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 9 | NW 10 | NW 10 | NW 10 | NW 9 | NW 9 | NW 11 | NW 9 | NW 8 | WNW 8 | NW 15 | NW 13 | NW 12 | NW 12 | NW 11 | NW 11 | NW 10 | NW 10 | NW 9 | WNW 5 |
Wave Graph  | ||||||||||||||||||||
 kJ | 412 | 416 | 311 | 241 | 135 | 74 | 55 | 118 | 70 | 44 | 75 | 609 | 645 | 593 | 445 | 326 | 200 | 113 | 83 | 56 |
Wind (km/h) | ||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross-on | glassy | cross-off | cross-on | cross-off | glassy | cross-on | glassy | glassy | cross-on | cross | glassy | on | cross | glassy | cross-on | cross | glassy | cross-on | cross-on |
High Tide | 4:14PM3.80m | 4:42AM3.65m | 4:56PM4.01m | 5:21AM3.80m | 5:36PM4.10m | 5:57AM3.86m | 6:12PM4.08m | 6:32AM3.83m | 6:48PM3.94m | 7:05AM3.73m | 7:21PM3.72m | 7:37AM3.56m | 7:55PM3.45m | |||||||
Low Tide | 10:22PM0.14m | 10:34AM0.21m | 11:03PM-0.04m | 11:14AM0.04m | 11:40PM-0.11m | 11:52AM-0.02m | 00:16AM-0.07m | 12:29PM0.02m | 00:51AM0.08m | 1:05PM0.15m | 1:25AM0.30m | 1:41PM0.37m | 1:59AM0.57m | |||||||
 |  |  |  | | | | | | | | | | | | | | | |  | |
 | — | — | 7:39 | — | — | 7:39 | — | — | 7:41 | — | — | 7:41 | — | — | 7:43 | — | — | 7:45 | — | — |
 | 8:28 | — | — | 8:25 | — | — | 8:24 | — | — | 8:22 | — | — | 8:21 | — | — | 8:19 | — | — | 8:16 | — |
mm | 1 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
Temp °C | 19 | 19 | 17 | 19 | 19 | 17 | 20 | 19 | 18 | 22 | 20 | 20 | 23 | 21 | 22 | 26 | 23 | 26 | 29 | 20 |
Feels °C | 16 | 17 | 16 | 18 | 18 | 18 | 19 | 19 | 19 | 21 | 20 | 21 | 22 | 22 | 22 | 25 | 24 | 26 | 28 | 19 |
Swell 1 Height (m) Direction Period (s) | NW 9 | NW 10 | NW 10 | NW 10 | NW 9 | NW 9 | NW 8 | NW 9 | NW 8 | WNW 8 | NW 7 | NW 13 | NW 12 | NW 12 | NW 11 | NW 11 | NW 10 | NW 10 | NW 9 | NW 9 |
| kJ | 412 | 416 | 311 | 241 | 135 | 74 | 42 | 118 | 70 | 44 | 34 | 609 | 645 | 593 | 445 | 326 | 200 | 113 | 83 | 27 |
Swell 2 Height (m) Direction Period (s) | NW 11 | — | — | — | W 11 | NW 13 | NW 11 | — | — | NW 8 | NW 10 | — | — | — | — | — | WNW 10 | W 9 | W 9 | WNW 12 |
| kJ | 60 | — | — | — | 2 | 7 | 55 | — | — | 3 | 47 | — | — | — | — | — | 10 | 6 | 6 | 56 |
Swell 3 Height (m) Direction Period (s) | — | — | — | — | — | W 10 | — | — | — | NW 18 | NW 15 | — | — | — | — | — | — | — | NW 13 | W 8 |
| kJ | — | — | — | — | — | 2 | — | — | — | 12 | 75 | — | — | — | — | — | — | — | 7 | 5 |
Wind waves Height (m) Direction Period (s) | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | WNW 5 |
| kJ | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 56 |
Nearest Offshore or Glassy | ||||||||||||||||||||
Distance (km) | 197 | 0 | 0 | 87 | 0 | 1 | 87 | 0 | 1 | 197 | 12 | 0 | 87 | 6 | 0 | 11 | 11 | 0 | 606 | 39 |
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