Surf Forecasts:
Guethary - Les Alcyons/Avalanche surf forecast from 6 Sep 2026:
- Best quality surf: Monday 7 Sep, 8PM (local time) - 3ft (0.9m), 13s period, WNW swell with glassy winds.
- Most powerful swell: Wednesday 9 Sep, 5AM (local time) - 6.5ft (2.0m), 9s period, NW swell with 612 kJ wave energy.
- Next surfable swell (1★+): Monday 7 Sep, 8PM (local time) - 3ft (0.9m), 13s period with WNW 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 07) at 8PM. The primary swell is predicted to be 0.9m and 13s period with a secondary swell of 0.6m and 9s. 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 2.0m 9s and forecast to arrive on Wednesday (Sep 09) at 5AM. Winds are predicted to be cross-onshore at the time the swell arrives.
| Wave Type | Time (CEST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 8PM (Mon 7th Sep) | 3ft (0.9m) 13s |
| Best Surf | 8PM (Mon 7th Sep) | 3ft (0.9m) 13s |
| Most Powerful | 5AM (Wed 9th Sep) | 6.5ft (2.0m) 9s |
Table - best surf conditions forecast for Guethary - Les Alcyons/Avalanche over the next 16 days.
The Lowdown
Hey, Rusty here. Let’s break down what’s in store for Guethary - Les Alcyons/Avalanche.
The start of the period is pretty average. There’s some swell, but the wind is mostly onshore or cross-onshore, so conditions are going to be rough. The water temp is 74°, which is much warmer than usual for this time of year, so you might not need the thickest suit.
The first real standout is the morning of Thursday, September 10th. We’ve got a 5ft NW swell with an 11-second period and glassy conditions thanks to a light NE breeze. That’s the clean, lined-up stuff we want. The combined energy is moderate at 400. This is an expert-only reef break, so not one for the beginners.
Things get messy again until Sunday, September 13th. That morning looks clean and glassy, but the swell is only 2ft. However, the period jumps to 13 seconds, a nice long groundswell, with a combined energy of 257. It’ll be small but very clean.
Looking into the second week, the morning of Tuesday, September 15th is the one to watch. We’re looking at a 4ft NW swell, 12-second period, and glassy conditions with a light SW wind. The combined energy is a solid 494. It’s a long way out, so don’t bank on it, but if it comes together, that’s the best session on offer.
Beyond that, there are a few clean mornings with tiny waves, like the 20th and 21st. Those are more for a quiet paddle. Expect long lulls between sets with that long-period groundswell.
So, not a classic run. The only real windows are Thursday the 10th and Tuesday the 15th.
Rusty.
Short Range ForecastLight rain (total 9mm), mostly falling on Tue night. Warm (max 29°C on Sun afternoon, min 17°C on Mon night). Wind will be generally light. | Days 5-7 Weather SummarySome drizzle, heaviest during Wed afternoon. Warm (max 20°C on Fri afternoon, min 14°C on Thu morning). Wind will be generally light. | |||||||||||||||||||
Sun 6 | Monday 7 | Tuesday 8 | Wednesday 9 | Thursday 10 | Friday 11 | Saturday 12 | ||||||||||||||
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 10 | NW 10 | WNW 14 | WNW 12 | WNW 11 | WNW 11 | NW 9 | NW 9 | NW 9 | NW 10 | NW 10 | NW 10 | NW 9 | NW 9 | NW 10 | NW 9 | NW 8 | NW 8 | WNW 9 |
Wave Graph  | ||||||||||||||||||||
 kJ | 422 | 260 | 181 | 217 | 341 | 226 | 222 | 396 | 554 | 402 | 484 | 400 | 279 | 138 | 78 | 160 | 110 | 65 | 48 | 53 |
Wind (km/h) | ||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | on | cross-on | cross-on | on | cross | cross-on | cross-on | cross-on | cross-on | cross-on | cross-off | glassy | on | glassy | glassy | cross-on | glassy | glassy | cross-on | cross-off |
High Tide | 1:56AM2.90m | 2:24PM3.19m | 3:05AM3.16m | 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 | ||||||||
Low Tide | 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 | 11:14AM0.04m | 11:40PM-0.11m | 11:52AM-0.02m | 00:16AM-0.07m | |||||||
 |  |  | |  | | |  |  | | |  | | | | | | | | | |
 | — | — | 7:35 | — | — | 7:37 | — | — | 7:37 | — | — | 7:39 | — | — | 7:39 | — | — | 7:41 | — | — |
 | 8:34 | — | — | 8:31 | — | — | 8:30 | — | — | 8:28 | — | — | 8:25 | — | — | 8:24 | — | — | 8:22 | — |
mm | — | — | — | — | — | — | — | 6 | 3 | 1 | — | — | — | — | — | — | — | — | — | — |
Temp °C | 29 | 21 | 20 | 22 | 20 | 20 | 22 | 20 | 18 | 19 | 19 | 17 | 19 | 18 | 17 | 20 | 19 | 20 | 25 | 23 |
Feels °C | 28 | 21 | 22 | 23 | 22 | 21 | 22 | 20 | 17 | 15 | 16 | 17 | 17 | 17 | 18 | 19 | 19 | 20 | 23 | 24 |
Swell 1 Height (m) Direction Period (s) | NW 11 | NW 10 | NW 10 | NW 9 | WNW 12 | WNW 11 | WNW 11 | W 8 | NW 9 | NW 9 | NW 10 | NW 10 | NW 10 | NW 9 | NW 9 | NW 10 | NW 9 | NW 8 | NW 8 | WNW 9 |
| kJ | 422 | 260 | 181 | 135 | 341 | 226 | 222 | 37 | 554 | 402 | 484 | 400 | 279 | 138 | 78 | 160 | 110 | 65 | 48 | 53 |
Swell 2 Height (m) Direction Period (s) | — | W 19 | WNW 16 | WNW 14 | — | — | — | — | — | NW 11 | — | — | — | W 11 | WNW 12 | — | N 3 | N 4 | — | NNW 4 |
| kJ | — | 7 | 142 | 217 | — | — | — | — | — | 61 | — | — | — | 2 | 14 | — | 2 | 1 | — | 2 |
Swell 3 Height (m) Direction Period (s) | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | NW 15 |
| kJ | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 9 |
Wind waves Height (m) Direction Period (s) | — | — | — | — | — | — | — | NW 9 | — | — | — | — | — | — | — | — | — | — | — | — |
| kJ | — | — | — | — | — | — | — | 396 | — | — | — | — | — | — | — | — | — | — | — | — |
Nearest Offshore or Glassy | ||||||||||||||||||||
Distance (km) | 12 | 12 | 12 | 12 | 6 | 12 | 12 | 147 | 91 | 110 | 0 | 0 | 87 | 0 | 1 | 87 | 0 | 1 | 325 | 2 |
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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