Surf Forecasts:
Guethary - Les Alcyons/Avalanche surf forecast from 14 Sep 2026:
- Best quality surf: Saturday 19 Sep, 5AM (local time) - 8ft (2.4m), 14s period, NW swell with cross-offshore winds.
- Most powerful swell: Saturday 19 Sep, 2AM (local time) - 8ft (2.4m), 14s period, NW swell with 2,190 kJ wave energy.
- Next surfable swell (1★+): Tuesday 15 Sep, 2AM (local time) - 3.5ft (1.0m), 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 Tuesday (Sep 15) at 2AM. The primary swell is predicted to be 1.0m 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 2.4m 14s and forecast to arrive on Saturday (Sep 19) at 2AM. Winds are predicted to be cross-shore at the time the swell arrives.
| Wave Type | Time (CEST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 2AM (Tue 15th Sep) | 3.5ft (1.0m) 10s |
| Best Surf | 5AM (Sat 19th Sep) | 8ft (2.4m) 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, let’s run through this in feet and Fahrenheit.
First few days are a total bust. From Monday the 14th through Friday the 18th, it’s all choppy cross-onshore wind and tiny, weak swell. Water temp is about 73°, which is much warmer than average for this time of year, running about 5° above normal.
Things finally turn on Saturday the 19th. That morning, Guethary - Les Alcyons/Avalanche (reef break, experts only) gets a clean 7ft NW swell with a solid 13-second period, and a light offshore breeze out of the ENE. The combined energy is cranking at 1514, that’s strong to very strong. This is the standout session of the whole 16 days – powerful, lined-up waves, but only for experienced surfers. It’s a popular, consistent spot, so expect a crowd.
Sunday the 20th morning goes glassy with a 5ft NW swell, 12-second period, energy at 528. Clean and fun. Monday 21st and Tuesday 22nd mornings are also glassy with 5ft and 4ft NW swells respectively, good period. Those are your other solid windows, but Saturday morning is the big one.
After that, the swell dies. A small, glassy bump on Friday the 25th morning gives you 4ft from the NW, 12-second period, energy at 373 – rideable but ordinary. Then it’s back to tiny, weak, and cross-onshore mush until the end of the forecast on the 29th.
So for the experts, lock in Saturday the 19th morning. Sunday through Tuesday mornings are also worth a paddle. The rest is a whole lot of nothing.
Rusty.
Short Range ForecastLight rain (total 5mm), mostly falling on Tue night. Warm (max 28°C on Mon afternoon, min 17°C on Wed night). Wind will be generally light. | Days 5-7 Weather SummaryLight rain (total 7mm), mostly falling on Fri afternoon. Warm (max 20°C on Sat afternoon, min 15°C on Sat morning). Wind will be generally light. | |||||||||||||||||||
Mon 14 | Tuesday 15 | Wednesday 16 | Thursday 17 | Friday 18 | Saturday 19 | Sunday 20 | ||||||||||||||
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 | NW 9 | WNW 5 | WNW 10 | NW 8 | NW 9 | NW 11 | NW 11 | NW 10 | NW 10 | NW 9 | NW 14 | NW 13 | NW 13 | NW 12 | NW 12 | NW 11 | NW 11 |
Wave Graph  | ||||||||||||||||||||
 kJ | 286 | 212 | 133 | 55 | 51 | 130 | 264 | 284 | 663 | 604 | 388 | 177 | 359 | 2190 | 1514 | 1279 | 748 | 528 | 414 | 399 |
Wind (km/h) | ||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross-on | cross-off | cross-on | cross-on | on | cross-on | on | cross | on | on | cross-on | cross-on | on | cross | cross-off | cross-on | glassy | glassy | cross-on | cross-off |
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 | 1:25AM0.30m | 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 | ||||||||
 |  | | |  |  |  | | | | |  | |  | | | | | | | |
 | — | — | 7:45 | — | — | 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 | 2 | — | 2 | — | — | 3 | 2 | 2 | — | — | — | — | — | — | — |
Temp °C | 28 | 24 | 22 | 22 | 20 | 19 | 19 | 18 | 18 | 19 | 18 | 18 | 19 | 18 | 17 | 20 | 19 | 18 | 22 | 20 |
Feels °C | 26 | 24 | 20 | 21 | 20 | 19 | 17 | 17 | 18 | 17 | 17 | 17 | 18 | 16 | 16 | 18 | 19 | 18 | 20 | 20 |
Swell 1 Height (m) Direction Period (s) | NW 11 | NW 10 | NW 10 | NW 9 | WNW 5 | WNW 10 | NW 8 | NW 9 | NW 11 | NW 11 | NW 10 | NW 10 | NW 9 | NW 14 | NW 13 | NW 13 | NW 12 | NW 12 | NW 11 | NW 11 |
| kJ | 286 | 212 | 133 | 55 | 51 | 130 | 264 | 284 | 663 | 604 | 388 | 177 | 359 | 2190 | 1514 | 1279 | 748 | 528 | 414 | 399 |
Swell 2 Height (m) Direction Period (s) | — | — | W 9 | WNW 12 | NW 9 | — | — | NW 12 | — | — | — | WNW 6 | NW 16 | — | — | — | — | — | — | N 4 |
| kJ | — | — | 7 | 15 | 38 | — | — | 244 | — | — | — | 57 | 260 | — | — | — | — | — | — | 6 |
Swell 3 Height (m) Direction Period (s) | — | — | W 13 | — | WNW 11 | — | — | — | — | — | — | NW 17 | NW 12 | — | — | — | — | — | — | — |
| kJ | — | — | 4 | — | 48 | — | — | — | — | — | — | 11 | 53 | — | — | — | — | — | — | — |
Wind waves Height (m) Direction Period (s) | N 4 | — | — | WNW 5 | — | NW 6 | — | — | — | — | — | — | — | — | — | — | — | — | N 4 | — |
| kJ | 1 | — | — | 45 | — | 88 | — | — | — | — | — | — | — | — | — | — | — | — | 3 | — |
Nearest Offshore or Glassy | ||||||||||||||||||||
Distance (km) | 11 | 0 | 12 | 597 | 12 | 125 | 87 | 6 | 1 | 147 | 12 | 12 | 87 | 1 | 0 | 87 | 0 | 0 | 87 | 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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