Surf Forecasts:
Guethary - Les Alcyons/Avalanche surf forecast from 8 Sep 2026:
- Best quality surf: Sunday 13 Sep, 5AM (local time) - 4ft (1.2m), 13s period, NW swell with cross-offshore winds.
- Most powerful swell: Sunday 13 Sep, 11AM (local time) - 5ft (1.5m), 13s period, NW swell with 721 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 cross-offshore as the swell arrives.
The most powerful waves expected at Guethary - Les Alcyons/Avalanche in the next 16 days are 1.5m 13s and forecast to arrive on Sunday (Sep 13) at 11AM. 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+) | 2AM (Thu 10th Sep) | 5ft (1.5m) 10s |
| Best Surf | 5AM (Sun 13th Sep) | 4ft (1.2m) 13s |
| Most Powerful | 11AM (Sun 13th Sep) | 5ft (1.5m) 13s |
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 Guethary - Les Alcyons/Avalanche.
Right out of the gate, we’ve got a bit of a flat spell to deal with. The ocean is pretty much a washing machine for the first few days, with poor conditions and no real call to get wet. That first true chance for a surf doesn’t show up until Thursday morning the 10th of September.
Thursday morning is worth a look. The swell is a clean 4ft from the NW, with a period of 10 seconds. The big news is the wind: glassy, offshore out of the E at just 3 mph. The water temp is sitting at 74°, which is much warmer than normal for this time of year—nearly 5° warmer, so you can leave the thick rubber at home. The combined energy is moderate (311). It’s not massive, but it’s clean and you’ll get some fun ones.
The real standout, though, is Sunday morning the 13th of September. This is the one to circle on the calendar. We’ve got a solid 5ft of NW swell, but the period jumps to 13 seconds—that’s a proper groundswell with some real push. The combined energy is strong (721). Wind is glassy again, with a light E/NE breeze at 3 mph. The wave comment says very good surf conditions, and for a reef break like this, that long-period swell is going to set up some lovely, lined-up waves. This is an expert break, and with that size, it’s not for the beginners—but for those who know the place, this is the morning to be out there.
Monday morning the 14th also holds some promise with a clean 4ft, 12-second swell and glassy conditions, but it’s a step down from Sunday.
After that, the second week gets a bit messy. There’s a pulse of bigger swell on Wednesday the 16th with 7ft, but the wind is cross-onshore and choppy, so it’s a miss. Thursday the 17th has some size but marginal conditions. You’ll see a few glassy mornings here and there with small, surfable waves, but nothing to get too excited about. The pattern fades out towards the end of the window.
So, bottom line: the first few days are a write-off, but Thursday morning and especially Sunday morning the 13th are your best bets. Get on it while the wind plays nice.
Rusty.
Short Range ForecastModerate rain (total 12mm), heaviest on Tue night. Warm (max 22°C on Tue afternoon, min 15°C on Wed night). Wind will be generally light. | Days 5-7 Weather SummaryMostly dry. Warm (max 25°C on Sun afternoon, min 16°C on Fri night). Wind will be generally light. | |||||||||||||||||||
Tue 8 | Wednesday 9 | Thursday 10 | Friday 11 | Saturday 12 | Sunday 13 | Monday 14 | ||||||||||||||
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 11 | NW 9 | NW 9 | NW 9 | NW 10 | NW 10 | NW 10 | NW 9 | NW 9 | NW 11 | WNW 9 | WNW 8 | WNW 8 | NW 10 | NW 13 | NW 12 | NW 12 | NW 12 | NW 11 | NW 10 |
Wave Graph  | ||||||||||||||||||||
 kJ | 222 | 491 | 497 | 379 | 408 | 311 | 241 | 114 | 74 | 55 | 138 | 92 | 59 | 139 | 721 | 645 | 624 | 469 | 319 | 212 |
Wind (km/h) | ||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | on | on | on | cross-on | cross-off | glassy | cross-on | glassy | cross-on | on | glassy | glassy | on | glassy | glassy | cross-on | cross | glassy | cross-on | cross-off |
High Tide | 3:25PM3.51m | 3:58AM3.43m | 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 | |||||||
Low Tide | 9:35PM0.40m | 9:50AM0.46m | 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 | |||||||
 |  |  | |  | |  | | | | | | | | | | | | | | |
 | — | — | 7:37 | — | — | 7:39 | — | — | 7:39 | — | — | 7:41 | — | — | 7:41 | — | — | 7:43 | — | — |
 | 8:30 | — | — | 8:28 | — | — | 8:25 | — | — | 8:24 | — | — | 8:22 | — | — | 8:21 | — | — | 8:19 | — |
mm | — | 10 | 1 | 1 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
Temp °C | 22 | 21 | 19 | 19 | 18 | 18 | 20 | 18 | 18 | 20 | 19 | 18 | 21 | 20 | 20 | 25 | 22 | 22 | 27 | 24 |
Feels °C | 22 | 22 | 18 | 18 | 15 | 18 | 18 | 17 | 18 | 20 | 19 | 19 | 20 | 21 | 21 | 24 | 22 | 21 | 24 | 24 |
Swell 1 Height (m) Direction Period (s) | WNW 11 | NW 9 | NW 9 | NW 9 | NW 10 | NW 10 | NW 10 | NW 9 | NW 9 | NW 8 | WNW 9 | WNW 8 | WNW 8 | NW 10 | NW 13 | NW 12 | NW 12 | NW 12 | NW 11 | NW 10 |
| kJ | 222 | 491 | 497 | 379 | 408 | 311 | 241 | 114 | 74 | 42 | 138 | 92 | 59 | 139 | 721 | 645 | 624 | 469 | 319 | 212 |
Swell 2 Height (m) Direction Period (s) | — | — | — | NW 11 | — | — | — | W 11 | NW 13 | NW 11 | — | — | NW 18 | NW 15 | — | — | — | — | — | — |
| kJ | — | — | — | 60 | — | — | — | 2 | 7 | 55 | — | — | 12 | 134 | — | — | — | — | — | — |
Swell 3 Height (m) Direction Period (s) | — | — | — | — | — | — | — | — | W 11 | — | — | — | — | — | — | — | — | — | — | — |
| kJ | — | — | — | — | — | — | — | — | 2 | — | — | — | — | — | — | — | — | — | — | — |
Wind waves Height (m) Direction Period (s) | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| kJ | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
Nearest Offshore or Glassy | ||||||||||||||||||||
Distance (km) | 12 | 147 | 54 | 197 | 0 | 0 | 87 | 0 | 26 | 87 | 0 | 1 | 197 | 0 | 0 | 87 | 6 | 0 | 47 | 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.
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