Surf Forecasts:
Guethary - Les Alcyons/Avalanche surf forecast from 4 Sep 2026:
- Best quality surf: Saturday 5 Sep, 8PM (local time) - 5ft (1.6m), 13s period, NW swell with glassy winds.
- Most powerful swell: Sunday 6 Sep, 2AM (local time) - 6ft (1.8m), 13s period, NW swell with 990 kJ wave energy.
- Next surfable swell (1★+): Saturday 5 Sep, 8AM (local time) - 3ft (0.9m), 9s 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 Saturday (Sep 05) at 8AM. The primary swell is predicted to be 0.9m and 9s period with a secondary swell of 0.1m and 16s. 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 13s and forecast to arrive on Sunday (Sep 06) at 2AM. Winds are predicted to be offshore at the time the swell arrives.
| Wave Type | Time (CEST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 8AM (Sat 5th Sep) | 3ft (0.9m) 9s |
| Best Surf | 8PM (Sat 5th Sep) | 5ft (1.6m) 13s |
| Most Powerful | 2AM (Sun 6th Sep) | 6ft (1.8m) 13s |
Table - best surf conditions forecast for Guethary - Les Alcyons/Avalanche over the next 16 days.
The Lowdown
Alright mates, Rusty here, breaking it down in feet and freedom units.
The only spot in the game is Guethary - Les Alcyons/Avalanche. It’s a serious expert-only reef, reliable as they come, but it’s a picky wave. For the first few days, it’s a tease. Friday morning the 4th is glassy flat, with a weak 2ft WNW windswell (8-second period), and the energy is a feeble 57. The water is 74°, which is way warmer than normal for this time of year, almost tropical. But there’s no surf to enjoy.
Saturday morning the 5th you finally get a clean window. 3ft of NW swell at 9 seconds, with a nice offshore ENE wind. The energy jumps to 229 (moderate). It’s small, but it’s clean. The afternoon swells to 5ft, with a long 13-second period (732 energy), but the wind turns cross-on and ruins the shape. That’s the biggest swell of the forecast, and the wind screws it.
The absolute stand-out is Thursday morning the 10th. Glassy, dead calm. A solid 4ft NW swell with a 10-second period, carrying 308 energy. That’s the ticket. The reef is exposed to the NW, so it’ll be holding nice, lined-up sets. The crowd is a problem though – it’s often packed, so you’ll be competing for waves.
Friday morning the 11th is a similar glassy morning, with a slightly smaller 4ft NW swell. Another good call.
After that, it’s a slow fade. Wednesday morning the 16th is glassy, but the swell is down to 3ft with weak energy (185). Surfable, but nothing to write home about. The rest of the run is small and wind-affected, with the 19th showing a pathetic 1ft. The window is short. Thursday the 10th is your best shot. Friday the 11th is a decent second. The water is warm, but the wind is the enemy most of the time.
Rusty.
Short Range ForecastMostly dry. Warm (max 29°C on Sat afternoon, min 18°C on Sat morning). Wind will be generally light. | Days 4-6 Weather SummaryModerate rain (total 14mm), heaviest on Tue afternoon. Warm (max 22°C on Mon afternoon, min 14°C on Wed night). Wind will be generally light. | ||||||||||||||||||||
Friday 4 | Saturday 5 | Sunday 6 | Monday 7 | Tuesday 8 | Wednesday 9 | Thursday 10 | |||||||||||||||
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) | WNW 8 | NW 8 | WNW 9 | NW 9 | NW 13 | NW 13 | NW 12 | NW 11 | NW 10 | NW 10 | WNW 14 | WNW 12 | WNW 11 | WNW 11 | NW 10 | NW 12 | NW 11 | NW 11 | NW 10 | NW 10 | NW 10 |
Wave Graph  | |||||||||||||||||||||
 kJ | 38 | 72 | 99 | 118 | 732 | 990 | 723 | 466 | 226 | 181 | 223 | 399 | 256 | 222 | 235 | 200 | 466 | 487 | 308 | 231 | 113 |
Wind (km/h) | |||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | glassy | cross-on | glassy | cross-off | cross-on | off | cross-on | cross-on | cross-on | cross-on | on | cross-on | on | cross-on | cross-on | cross | cross-on | cross-off | glassy | glassy | cross |
High Tide | 9:59AM3.06m | 10:42PM2.90m | 11:21AM2.90m | 00:20AM2.78m | 1:01PM2.94m | 1:56AM2.90m | 2:24PM3.19m | 3:05AM3.16m | 3:25PM3.51m | 3:58AM3.43m | 4:14PM3.80m | 4:42AM3.65m | 4:56PM4.01m | ||||||||
Low Tide | 4:17PM0.92m | 4:53AM1.11m | 5:44PM1.06m | 6:25AM1.19m | 7:21PM0.98m | 7:53AM1.03m | 8:38PM0.71m | 8:59AM0.75m | 9:35PM0.40m | 9:50AM0.46m | 10:22PM0.14m | 10:34AM0.21m | 11:03PM-0.04m | ||||||||
 | |  |  |  |  | | | | | | |  |  |  | | |  | | | | |
 | 7:31 | — | — | 7:33 | — | — | 7:35 | — | — | 7:35 | — | — | 7:37 | — | — | 7:37 | — | — | 7:39 | — | — |
 | — | 8:37 | — | — | 8:35 | — | — | 8:34 | — | — | 8:31 | — | — | 8:30 | — | — | 8:28 | — | — | 8:25 | — |
mm | — | — | — | — | — | — | — | — | — | — | — | — | 1 | 3 | 7 | 3 | — | — | — | — | — |
Temp °C | 27 | 26 | 22 | 21 | 29 | 29 | 24 | 26 | 21 | 20 | 22 | 20 | 20 | 19 | 18 | 18 | 19 | 18 | 16 | 20 | 19 |
Feels °C | 27 | 25 | 23 | 21 | 28 | 28 | 24 | 27 | 22 | 22 | 23 | 21 | 21 | 20 | 18 | 17 | 16 | 16 | 16 | 19 | 17 |
Swell 1 Height (m) Direction Period (s) | WNW 8 | NW 8 | WNW 9 | NW 9 | NW 13 | NW 13 | NW 12 | NW 11 | NW 10 | NW 10 | NW 9 | WNW 12 | WNW 11 | WNW 11 | NW 10 | NW 9 | NW 11 | NW 11 | NW 10 | NW 10 | NW 10 |
| kJ | 38 | 72 | 99 | 118 | 732 | 990 | 723 | 466 | 226 | 181 | 118 | 399 | 256 | 222 | 235 | 155 | 466 | 487 | 308 | 231 | 113 |
Swell 2 Height (m) Direction Period (s) | NW 8 | N 4 | — | NW 11 | — | — | — | — | — | WNW 16 | WNW 14 | — | — | — | — | NW 12 | — | — | — | — | — |
| kJ | 18 | 1 | — | 77 | — | — | — | — | — | 84 | 223 | — | — | — | — | 200 | — | — | — | — | — |
Swell 3 Height (m) Direction Period (s) | N 4 | — | — | NW 15 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| kJ | 1 | — | — | 34 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
Wind waves Height (m) Direction Period (s) | — | — | — | — | — | — | — | — | — | — | — | — | — | NNW 5 | — | — | — | — | — | — | — |
| kJ | — | — | — | — | — | — | — | — | — | — | — | — | — | 72 | — | — | — | — | — | — | — |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 1 | 196 | 1 | 0 | 11 | 0 | 12 | 12 | 12 | 12 | 87 | 12 | 49 | 87 | 6 | 6 | 87 | 0 | 0 | 0 | 13 |
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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