Guethary - Les Alcyons/Avalanche Surf Break

Lat Long: 43.43° N 1.62° W

Guethary - Les Alcyons/Avalanche Surf Forecast and Surf Report

Issued: 1 am 25 Aug 2026 (local time)

Forecast update in  hr  min

Today's Guethary - Les Alcyons/Avalanche sea temperature is
24.3°C
2.7° 

Guethary - Les Alcyons/Avalanche surf forecast is for near shore open water. Breaking waves will often be smaller at less exposed spots.


Guethary - Les Alcyons/Avalanche surf forecast from 25 Aug 2026:

  • Best quality surf: Saturday 29 Aug, 5AM (local time) - 6.5ft (2.0m), 10s period, WNW swell with cross-offshore winds.
  • Most powerful swell: Friday 28 Aug, 11PM (local time) - 7.5ft (2.3m), 10s period, WNW swell with 1,045 kJ wave energy.
  • Next surfable swell (1★+): Thursday 27 Aug, 8PM (local time) - 3ft (0.9m), 8s 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 Thursday (Aug 27) at 8PM. The primary swell is predicted to be 0.9m and 8s period with a secondary swell of 0.1m and 12s. 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 2.3m 10s and forecast to arrive on Friday (Aug 28) at 11PM. Winds are predicted to be cross-onshore at the time the swell arrives.

Wave TypeTime (CEST) & Date Wave Height & Period
Next good surf (1 star+) 8PM (Thu 27th Aug)3ft (0.9m) 8s
Best Surf 5AM (Sat 29th Aug)6.5ft (2.0m) 10s
Most Powerful11PM (Fri 28th Aug)7.5ft (2.3m) 10s

Table - best surf conditions forecast for Guethary - Les Alcyons/Avalanche over the next 16 days.


The Lowdown

Alright folks, Rusty here, looking at the local scene. We’ve got one spot on the radar for the next couple of weeks, and it’s a ripper of a reef setup that’s only for the brave. It’s going to be a bit of a waiting game for the real magic, but when it comes, it’ll be worth the wait.

For the next week or so, honestly, don’t get wet. From now through the end of August, the swell is tiny and the conditions are messy. We’re looking at weak, short-period junk in the 1 to 2 ft range with mostly onshore or cross-onshore winds. The energy levels are pathetic, barely breaking triple digits (25 to 61). A few mornings might look clean or glassy, but there’s just no power behind it. The swell is poor, so give the boards a rest.

We start to see a pulse of energy pick up around the 28th of August. Friday morning the swell jumps to 6 ft, but it’s coming with a stiff cross-shore and a combined energy of 365, which is moderate but not clean. The wind is all over the place, so while it’s bigger, the quality isn’t there yet.

Now, here’s where it gets interesting. The standout session looks to be Saturday the 29th, first light. We’ve got a 5 ft NW groundswell with a clean 9-second period, and the wind is a light easterly, giving us a clean, cross-offshore flow. The energy is pumping at 388, and for a reef this exposed, that’s solid. This is the best on offer in the early window – it’s the one to aim for. Expect a buttery morning with decent, powerful waves. Later that afternoon the wind swings north and messes it up, so it’s a morning-only strike.

There’s another big gap of poor conditions after that until the 1st of September. Tuesday the 1st of September morning is looking very promising. We’ve got a sweet 6 ft NW groundswell, a 10-second period, and clean cross-offshore easterly winds. The combined energy is cranking at 628, making for some moderate to strong wave energy. This is a solid, proper groundswell for the point.

The real beast, though, is sitting out there for the 8th of September. That Tuesday morning is showing a massive 13 ft WNW swell with a 10-second period and glassy conditions. The combined energy is an insane 3476, which is very strong. This is a big, powerful swell, and for a reef like this, only experts should even think about it. It will be huge, clean, and dangerous. The confidence is lower this far out, but if it comes together, it will be the wave of the month. The following Wednesday the 9th still has solid 6 ft energy but the wind is more onshore and messy.

This spot is a consistent, expert-only reef break. It’s exposed to the west and the optimum swell is from the west, so that big WNW swell is dead on. Be warned, it gets *often* crowded, so for the best sessions, you’ll be in a pack. Also, the water is unusually warm right now; the anomaly is 3°C above normal, so it’s much warmer than usual for late August.

For the kite surfers among ya, watch the afternoons. When that swell is over 5 ft with strong cross-onshore winds, like 28th August afternoon, it’s going to be more fun on a kite than a paddle board.

All in all, wait for Saturday the 29th morning, then mark your calendar for the 1st and 8th of September.

Cheers,
Rusty

Short Range Forecast

Some drizzle, heaviest during Tue morning. Warm (max 33°C on Wed afternoon, min 19°C on Tue night). Wind will be generally light.

Days 4-6 Weather Summary

Mostly dry. Warm (max 23°C on Fri afternoon, min 17°C on Sat morning). Wind will be generally light.

Tuesday
25
Wednesday
26
Thursday
27
Friday
28
Saturday
29
Sunday
30
Monday
31
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
Rating
(10 max)
0
0
0
0
0
0
0
0
0
0
0
2
2
0
2
1
0
0
0
0
3
Swell
Height Map
Height Map
Height Map
Height Map
Height Map
Height Map
Height Map
Height Map
Wave
Height (m)
Direction
Period (s)
0.6
WNW
4
0.3
NW
12
0.4
NW
11
0.4
NW
10
0.4
NW
10
0.4
WNW
9
0.4
NW
8
0.7
WNW
8
0.9
WNW
8
1.7
WNW
8
1.7
WNW
9
2.2
WNW
10
1.6
NW
9
1.4
NW
9
1.3
NW
8
1.3
WNW
8
1.3
WNW
8
0.8
NW
8
0.9
WNW
8
1.3
NW
10
1.6
NW
10
Wave Graph
Metric surfscale
Energy kJ
15
23
31
26
29
31
17
58
92
365
475
951
388
281
222
235
235
78
103
355
527
Wind (km/h)
15
W
10
NNW
5
SE
5
ESE
10
ESE
10
WSW
5
SSW
5
NNW
15
SW
15
SW
20
WNW
10
WSW
5
E
15
N
5
SSW
5
WNW
10
NNW
10
SW
10
NW
10
NNW
5
SE
Wind State
cross-on
on
glassy
cross-off
cross-off
cross-on
glassy
cross-on
cross
cross
on
cross
cross-off
cross-on
glassy
cross-on
on
cross
on
on
off
High Tide
4:05PM3.21m
4:26AM3.14m
4:39PM3.45m
4:59AM3.34m
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
Low Tide
9:43AM0.95m
10:11PM0.74m
10:20AM0.71m
10:46PM0.50m
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
rain showers
part cloud
part cloud
cloud
part cloud
cloud
cloud
cloud
part cloud
clear
clear
clear
clear
clear
clear
clear
part cloud
clear
rain showers
rain showers
clear
<span class="translation_missing" title="translation missing: en.weather_tables.sunrise">Sunrise</span>
7:20
7:22
7:24
7:24
7:26
7:26
7:28
<span class="translation_missing" title="translation missing: en.weather_tables.sunset">Sunset</span>
8:53
8:52
8:51
8:49
8:47
8:45
8:44
 mm
1
1
1
Temp °C
23
24
22
23
33
28
22
24
22
21
23
21
20
23
21
21
22
21
21
21
20
Feels °C
23
24
24
24
31
27
23
24
23
17
19
20
20
22
21
22
22
21
22
21
20
  • Map Icons:
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  • Live Wave Height (m)
  • Live Wind Speed (km/h)
  • Surf Rating (10 Max)
  • Ocean Swells (m)
  • Wind Speed (km/h)
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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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