Surf Forecasts:
Guethary - Les Alcyons/Avalanche surf forecast from 10 Aug 2026:
- Most powerful swell: Sunday 16 Aug, 8PM (local time) - 3.5ft (1.1m), 7s period, NW swell with 140 kJ wave energy.
Best Forecast Surf Conditions for Guethary - Les Alcyons/Avalanche this week:
The most powerful waves expected at Guethary - Les Alcyons/Avalanche in the next 16 days are 1.1m 7s and forecast to arrive on Sunday (Aug 16) at 8PM. 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+) | - | - |
| Best Surf | - | - |
| Most Powerful | 8PM (Sun 16th Aug) | 3.5ft (1.1m) 7s |
Table - best surf conditions forecast for Guethary - Les Alcyons/Avalanche over the next 16 days.
The Lowdown
Alright crew, Rusty here. Let’s talk about the surf.
The water is warm, sitting at about 75°F, which is a few degrees warmer than usual for this time of year—comfortable without a full wetsuit.
We’ve got a real dry spell on our hands. From Monday the 10th through Saturday the 16th, it’s mostly flat or tiny, with weak onshore winds. The swell is small, like 1 to 2 feet, and the wind is mostly onshore, so the ocean is messy and uninviting. The energy is weak (combined energy around 57 to 129), and the period is short, so no real power or shape.
Sunday the 16th morning gives us a glassy window with 3 feet of weak NW swell, but it’s still not enough to get excited about. You’ll be waiting.
The first real sign of life comes on Thursday the 20th. The morning has a light cross-off breeze from the ENE, and the swell bumps up to 2 feet from the NW with a 10-second period. The combined energy hits 129 (moderate), and the wave comment says “surfable but ordinary.” After a week of nothing, this is a welcome change.
The standout is Monday the 24th. The morning swell jumps to 5 feet from the NW, 10-second period, and the combined energy is a massive 520 (very strong). The wind is onshore from the NNW, so it’s not clean, but for experts on a reef break like Guethary - Les Alcyons/Avalanche, that’s a serious amount of water moving. The afternoon is a bit smaller at 5 feet, but still onshore. This is big, powerful surf—only for the experienced.
Tuesday the 25th morning looks more user-friendly: glassy conditions with a north wind, 3 feet of NW swell, and combined energy at 196. That’s a fun, clean wave, though not the biggest.
So, the first week is a wash, then things pick up from the 20th. The 24th has the most power, but the wind is a problem. The 25th morning might be the best bet for a clean, manageable session.
Rusty out.
Short Range ForecastMostly dry. Warm (max 29°C on Wed afternoon, min 19°C on Tue morning). Wind will be generally light. | Days 4-6 Weather SummaryMostly dry. Warm (max 26°C on Thu afternoon, min 20°C on Thu night). Wind will be generally light. | ||||||||||||||||||||
Monday 10 | Tuesday 11 | Wednesday 12 | Thursday 13 | Friday 14 | Saturday 15 | Sunday 16 | |||||||||||||||
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) | NW 9 | NW 9 | NW 9 | NW 9 | NW 9 | NW 8 | NW 8 | WNW 10 | WNW 9 | W 10 | WNW 10 | WNW 11 | WNW 10 | WNW 10 | WNW 9 | WNW 9 | NW 7 | NW 7 | NW 8 | NW 8 | NW 7 |
Wave Graph  | |||||||||||||||||||||
 kJ | 81 | 81 | 81 | 76 | 59 | 55 | 57 | 34 | 28 | 50 | 32 | 93 | 77 | 72 | 65 | 53 | 82 | 54 | 90 | 125 | 69 |
Wind (km/h) | |||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross-on | on | glassy | glassy | on | cross | glassy | cross-on | cross | on | on | cross-on | on | on | cross-on | on | on | cross-on | glassy | on | cross |
High Tide | 3:31PM3.46m | 4:06AM3.43m | 4:25PM3.77m | 4:56AM3.64m | 5:13PM4.01m | 5:41AM3.78m | 5:57PM4.15m | 6:23AM3.83m | 6:38PM4.16m | 7:02AM3.79m | 7:18PM4.05m | 7:40AM3.68m | 7:56PM3.82m | ||||||||
Low Tide | 9:04AM0.74m | 9:41PM0.43m | 10:01AM0.47m | 10:34PM0.15m | 10:50AM0.23m | 11:22PM-0.05m | 11:34AM0.07m | 00:05AM-0.14m | 12:16PM-0.01m | 00:46AM-0.12m | 12:56PM0.03m | 1:25AM0.01m | 1:36PM0.16m | 2:03AM0.24m | |||||||
 |  |  | | | | | | | | | | | | | | | | | | | |
 | 7:05 | — | — | 7:05 | — | — | 7:07 | — | — | 7:07 | — | — | 7:09 | — | — | 7:09 | — | — | 7:11 | — | — |
 | — | — | 9:16 | — | — | 9:15 | — | — | 9:14 | — | — | 9:13 | — | — | 9:12 | — | — | 9:09 | — | — | 9:08 |
mm | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
Temp °C | 22 | 23 | 23 | 22 | 25 | 23 | 25 | 29 | 25 | 24 | 26 | 23 | 22 | 23 | 22 | 22 | 24 | 22 | 23 | 25 | 23 |
Feels °C | 24 | 25 | 25 | 24 | 27 | 25 | 28 | 30 | 28 | 26 | 28 | 25 | 24 | 24 | 23 | 24 | 26 | 23 | 26 | 27 | 25 |
Swell 1 Height (m) Direction Period (s) | NW 9 | NW 9 | NW 9 | NW 9 | NW 9 | NW 8 | NW 8 | NW 8 | WNW 9 | W 10 | WNW 10 | WNW 11 | WNW 10 | WNW 10 | WNW 9 | NW 6 | NW 7 | NW 7 | NW 8 | NW 8 | NW 7 |
| kJ | 81 | 81 | 81 | 76 | 59 | 55 | 57 | 28 | 28 | 50 | 32 | 93 | 77 | 72 | 65 | 32 | 82 | 54 | 90 | 125 | 69 |
Swell 2 Height (m) Direction Period (s) | W 7 | N 4 | — | NNW 4 | NNW 4 | WNW 10 | WNW 11 | WNW 10 | NW 8 | WNW 4 | WNW 12 | — | — | NW 4 | — | WNW 9 | WNW 8 | WNW 8 | — | — | NW 8 |
| kJ | 4 | 1 | — | 4 | 2 | 9 | 12 | 34 | 9 | 6 | 30 | — | — | 9 | — | 53 | 47 | 47 | — | — | 43 |
Swell 3 Height (m) Direction Period (s) | — | W 3 | — | W 11 | N 5 | W 13 | — | — | NNW 3 | N 4 | N 4 | — | — | — | — | — | — | — | — | — | — |
| kJ | — | 1 | — | 2 | 2 | 3 | — | — | 2 | 1 | 1 | — | — | — | — | — | — | — | — | — | — |
Wind waves Height (m) Direction Period (s) | NW 4 | — | — | — | — | — | — | — | WSW 3 | — | NW 4 | WNW 4 | WNW 4 | — | NW 6 | — | — | — | — | — | — |
| kJ | 3 | — | — | — | — | — | — | — | 3 | — | 4 | 8 | 9 | — | 42 | — | — | — | — | — | — |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 43 | 87 | 1 | 1 | 197 | 17 | 1 | 197 | 31 | 177 | 196 | 13 | 189 | 333 | 43 | 136 | 147 | 13 | 1 | 87 | 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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