Surf Forecasts:
Guethary - Les Alcyons/Avalanche surf forecast from 27 Aug 2026:
- Best quality surf: Monday 31 Aug, 11PM (local time) - 5.5ft (1.7m), 10s period, NW swell with glassy winds.
- Most powerful swell: Monday 31 Aug, 8PM (local time) - 5.5ft (1.7m), 10s period, NW swell with 569 kJ wave energy.
- Next surfable swell (1★+): Friday 28 Aug, 8PM (local time) - 3.5ft (1.1m), 8s 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 Friday (Aug 28) at 8PM. The primary swell is predicted to be 1.1m and 8s period with a secondary swell of 0.5m and 10s. 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 1.7m 10s and forecast to arrive on Monday (Aug 31) at 8PM. 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 (Fri 28th Aug) | 3.5ft (1.1m) 8s |
| Best Surf | 11PM (Mon 31st Aug) | 5.5ft (1.7m) 10s |
| Most Powerful | 8PM (Mon 31st Aug) | 5.5ft (1.7m) 10s |
Table - best surf conditions forecast for Guethary - Les Alcyons/Avalanche over the next 16 days.
The Lowdown
Alright, let’s talk surf for the next couple of weeks at Guethary - Les Alcyons/Avalanche—a reef break in the southwest. Water temp is 76°F, which is about 5°F warmer than usual for this time of year. That’s a warm anomaly, feels like a proper summer bath out there.
Right now, Thursday morning, it’s glassy flatness—swell is only 1ft from the northwest with a short 8-second period and weak energy (20). Nothing to ride. Thursday afternoon’s the same story.
Friday morning sees a slight bump to 3ft but cross-onshore wind from the WSW at 9 mph makes it choppy and messy. Friday afternoon goes to 4ft but still onshore wind and marginal conditions. Stay dry.
Saturday morning August 29th is the first real window. Glassy with an easterly breeze at 3 mph, 5ft swell from the WNW at 9 seconds, energy moderate at 354. Clean, glassy, and good. But Saturday afternoon the wind shifts NNW at 9 mph, cross-onshore and choppy—so get it early.
Sunday morning August 30th is another glassy morning: 5ft from the NW, 8 seconds, energy at 295. Clean. Sunday afternoon wind onshore again, ruins it.
Monday 31st is mixed—morning has some onshore wind but 5ft, afternoon sees 6ft with 10-second period, energy hitting 546, but wind onshore keeps it lumpy.
Tuesday 1st September morning is a standout. Cross-off wind from the ENE at 3 mph, 5ft from the WNW at 10 seconds, energy at 363, clean. That’s a nice session. Afternoon blown out again.
Quiet through Wednesday and Thursday with small waves and poor conditions.
Then Saturday 5th September morning—circle this one. Glassy, offshore cross-off wind from the east, 5ft from the NW with a long 12-second period, energy at 656. That’s proper groundswell, clean, and well-shaped. Sunday 6th September morning is also excellent—glassy, 5ft from the NW, 11 seconds, energy at 505.
Tuesday 8th September morning: 6ft from the NW, 11 seconds, cross-off wind from the east at 6 mph, energy at 708. Solid, clean, punchy. A bit bigger but still great for experienced surfers.
Thursday 10th September morning sees a bigger pulse—7ft from the NW at 9 seconds, energy at 715—but cross-onshore wind from the north at 6 mph makes it lumpy, and it’s getting big for most. Then it fades.
The best bets are Saturday 5th and Tuesday 8th September mornings—clean groundswell, good wind, and solid energy. Sunday 6th is also top notch. Saturday 29th August morning is a nice warm-up.
Rusty out.
Short Range ForecastMostly dry. Warm (max 25°C on Thu afternoon, min 18°C on Fri morning). Wind will be generally light. | Days 4-6 Weather SummaryMostly dry. Warm (max 23°C on Sun afternoon, min 17°C on Sun morning). Wind will be generally light. | ||||||||||||||||||||
Thursday 27 | Friday 28 | Saturday 29 | Sunday 30 | Monday 31 | Tuesday 1 | Wednesday 2 | |||||||||||||||
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 8 | NW 8 | WNW 8 | WNW 8 | WNW 8 | WNW 11 | WNW 9 | WNW 9 | WNW 8 | NW 8 | NW 10 | NW 10 | NW 9 | NW 10 | WNW 10 | WNW 10 | WNW 9 | NW 9 | NW 9 | NW 8 | NW 8 |
Wave Graph  | |||||||||||||||||||||
 kJ | 17 | 16 | 56 | 109 | 150 | 346 | 354 | 293 | 267 | 295 | 424 | 384 | 323 | 546 | 543 | 363 | 236 | 182 | 148 | 102 | 54 |
Wind (km/h) | |||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | glassy | on | cross-on | cross-on | on | cross-off | glassy | cross-on | glassy | glassy | on | glassy | on | on | glassy | cross-off | cross-on | cross-on | cross | cross-on | glassy |
High Tide | 5:10PM3.65m | 5:29AM3.50m | 5:41PM3.80m | 6:00AM3.62m | 6:13PM3.88m | 6:31AM3.68m | 6:45PM3.89m | 7:04AM3.68m | 7:19PM3.81m | 7:38AM3.61m | 7:56PM3.66m | 8:16AM3.47m | 8:38PM3.43m | ||||||||
Low Tide | 10:54AM0.49m | 11:18PM0.31m | 11:26AM0.32m | 11:50PM0.17m | 11:59AM0.21m | 00:22AM0.10m | 12:31PM0.16m | 00:54AM0.10m | 1:06PM0.19m | 1:28AM0.19m | 1:43PM0.29m | 2:06AM0.36m | 2:24PM0.46m | 2:49AM0.60m | |||||||
 |  |  |  | |  | | | | | | | | | | | | | | | | |
 | 7:24 | — | — | 7:24 | — | — | 7:26 | — | — | 7:26 | — | — | 7:28 | — | — | 7:28 | — | — | 7:30 | — | — |
 | — | 8:51 | — | — | 8:49 | — | — | 8:47 | — | — | 8:45 | — | — | 8:44 | — | — | 8:42 | — | — | 8:40 | — |
mm | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
Temp °C | 22 | 25 | 25 | 21 | 23 | 21 | 22 | 24 | 21 | 21 | 23 | 21 | 20 | 22 | 21 | 19 | 21 | 21 | 20 | 21 | 20 |
Feels °C | 23 | 25 | 23 | 18 | 20 | 20 | 22 | 22 | 22 | 21 | 22 | 22 | 21 | 22 | 22 | 19 | 20 | 21 | 20 | 20 | 20 |
Swell 1 Height (m) Direction Period (s) | NW 8 | NW 8 | WNW 8 | WNW 8 | WNW 8 | WNW 11 | WNW 9 | WNW 9 | WNW 8 | NW 8 | NW 10 | NW 10 | NW 9 | NW 10 | WNW 10 | WNW 10 | WNW 9 | NW 9 | NW 9 | NW 8 | NW 8 |
| kJ | 17 | 16 | 56 | 109 | 150 | 346 | 354 | 293 | 267 | 295 | 424 | 384 | 323 | 546 | 543 | 363 | 236 | 182 | 148 | 102 | 54 |
Swell 2 Height (m) Direction Period (s) | WNW 4 | WNW 5 | NW 11 | NW 10 | WNW 10 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | NNW 10 |
| kJ | 2 | 5 | 5 | 36 | 68 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 10 |
Swell 3 Height (m) Direction Period (s) | W 6 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| kJ | 1 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
Wind waves Height (m) Direction Period (s) | — | — | W 3 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| kJ | — | — | 3 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 347 | 84 | 31 | 12 | 87 | 0 | 0 | 87 | 0 | 0 | 147 | 0 | 113 | 87 | 0 | 0 | 87 | 54 | 1 | 197 | 1 |
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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