Guethary - Les Alcyons/Avalanche Surf Break

Lat Long: 43.43° N 1.62° W

Guethary - Les Alcyons/Avalanche Surf Forecast and Surf Report

Issued: 7 pm 20 Aug 2026 (local time)

Forecast update in  hr  min

Today's Guethary - Les Alcyons/Avalanche sea temperature is
25.2° C
3.4° 

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 20 Aug 2026:

  • Best quality surf: Friday 21 Aug, 11PM (local time) - 5ft (1.6m), 10s period, NW swell with glassy winds.
  • Most powerful swell: Friday 21 Aug, 11AM (local time) - 6ft (1.9m), 10s period, NW swell with 724 kJ wave energy.
  • Next surfable swell (1★+): Friday 21 Aug, 11PM (local time) - 5ft (1.6m), 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 Friday (Aug 21) at 11PM. The primary swell is predicted to be 1.6m and 10s period. 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 1.9m 10s and forecast to arrive on Friday (Aug 21) at 11AM. Winds are predicted to be cross-onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.4m 3s period and expected on Tuesday (Aug 25) at 8AM.

Wave TypeTime (CEST) & Date Wave Height & Period
Next good surf (1 star+)11PM (Fri 21st Aug)5ft (1.6m) 10s
Best Surf11PM (Fri 21st Aug)5ft (1.6m) 10s
Most Powerful11AM (Fri 21st Aug)6ft (1.9m) 10s

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


The Lowdown

Alright, Rusty here. Let’s cut the shit and get into it for the next couple of weeks.

Alright, so for this stretch we’re looking at one main spot: Guethary - Les Alcyons/Avalanche. It’s a reef setup over in France, and it needs an expert hand. We’re kicking off on Thursday, August 20th, but honestly, it’s a rough start. The first few days are a write-off – onshore junk and poor conditions. You’re waiting until Saturday the 22nd to even sniff anything worthwhile.

The Overall Picture
The real story here is a pulse of moderate to strong swell that rolls through, but the wind and conditions are going to be the fight the whole way. The water is running about 77°F, which is much warmer than normal for this time of year – a solid 6°F warmer than average. You can leave the 4/3 at home; this is boardies and a rashie territory if the sun’s out.

Saturday, August 22nd – The Only Real Window
If you’re paddling out, Saturday morning is your shot. The swell is a playful 4ft from the NW with a 9-second period. The energy is sitting at a moderate 269 (moderate wave energy). But the real beauty is the wind: it’s coming out of the east at 9 mph in a cross-offshore flow. That’s going to clean that reef right up. It’s an expert wave, so expect some heavy drops, but with those clean lines, it’ll be worth the paddle. Expect some company here though – this spot is *often* crowded, and for good reason on a day like this.

Sunday the 23rd to Around Thursday the 28th – A Blown-Out Mess
After that Saturday morning, it goes pear-shaped. Sunday is glassy but barely any swell (2ft). Then a bigger swell arrives on Thursday the 27th and Friday the 28th – we’re looking at 8ft from the WNW on Thursday afternoon (strong energy at 1007), and 7ft on Friday morning. But the wind is onshore or cross-onshore, so it’s going to be lumpy, choppy, and unridable for a standard surfer. That Thursday pulse is pushing past 8ft – that’s expert territory only, and with poor wind, even they’ll struggle. The reef will handle it, but the surface will be trash.

The Second Week (End of August into September)
The first few days of September are a flat spell. We see tiny waves (2ft to 3ft) and mostly onshore junk. It’s a proper lull from about the 30th of August through to the 3rd of September. Honestly, it’s just dead.

The Late, Late Hope – Thursday the 3rd & Friday the 4th of September
Hold on. There’s a little glimmer way out there. On Thursday morning, September 3rd, we get a 3ft NW swell with a light ENE cross-offshore breeze at 3 mph. It’s clean, but the energy is weak (111 – weak wave energy). It’s a long-range promise.

Then, Friday morning, September 4th looks interesting. It’s 5ft from the NW with an 8-second period. But the wind goes glass – dead flat. A NE breeze at 3 mph only. That’s the golden ticket. The energy is moderate at 281. If that holds, that’s the best of the second week, but it’s a long way out, so don’t plan your life around it.

The Verdict
The standout is Saturday the 22nd morning. That’s your day. After that, it’s a lot of cross and onshore wind ruining the fun until that glassy window on the 4th of September.

Stay frosty, and don't paddle out on the 27th unless you're a masochist or a pro.

- Rusty

Short Range Forecast

Heavy rain (total 22mm), heaviest during Thu night. Warm (max 30°C on Sun afternoon, min 16°C on Sat morning). Wind will be generally light.

Days 5-7 Weather Summary

Mostly dry. Warm (max 32°C on Mon afternoon, min 20°C on Sun night). Winds decreasing (fresh winds from the ESE on Mon afternoon, calm by Tue night).

Friday
21
Saturday
22
Sunday
23
Monday
24
Tuesday
25
Wednesday
26
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
Rating
(10 max)
1
0
1
2
2
0
1
0
0
0
0
0
0
0
0
2
0
0
0
Swell
Height Map
Height Map
Height Map
Height Map
Height Map
Height Map
Height Map
Height Map
Wave
Height (m)
Direction
Period (s)
1.5
NW
10
1.9
NW
10
1.8
NW
10
1.6
NW
10
1.2
NW
9
1.1
NW
9
1
NW
8
0.7
NW
7
0.5
NW
7
0.5
N
5
0.3
N
5
0.6
NW
6
0.3
NNW
3
0.1
NW
13
0.2
NNW
12
1.2
WNW
8
0.8
WNW
8
0.7
WNW
7
0.8
WNW
9
Wave Graph
Metric surfscale
Energy kJ
425
724
622
469
241
202
129
56
26
10
5
24
2
7
14
184
64
47
90
Wind (km/h)
10
W
15
WNW
15
WNW
5
S
15
E
20
NNE
10
SE
5
E
15
NNE
10
SE
10
SSE
30
ESE
10
SSW
10
SSW
10
NNW
0
W
5
ESE
5
NNE
10
SW
Wind State
cross-on
cross-on
cross-on
glassy
cross-off
cross
off
cross-off
cross-on
off
cross-off
off
cross-off
cross-off
cross-on
glassy
off
glassy
cross
High Tide
10:56PM2.63m
11:31AM2.63m
00:26AM2.48m
1:09PM2.59m
2:03AM2.54m
2:31PM2.73m
3:07AM2.71m
3:24PM2.96m
3:51AM2.93m
4:05PM3.21m
4:26AM3.14m
4:39PM3.45m
4:59AM3.34m
Low Tide
5:08AM1.36m
5:56PM1.38m
6:31AM1.47m
7:27PM1.38m
7:56AM1.39m
8:39PM1.22m
8:57AM1.19m
9:30PM0.99m
9:43AM0.95m
10:11PM0.74m
10:20AM0.71m
10:46PM0.50m
mod rain
rain showers
rain showers
part cloud
clear
clear
rain showers
clear
clear
part cloud
clear
part cloud
clear
part cloud
part cloud
cloud
part cloud
cloud
part cloud
<span class="translation_missing" title="translation missing: en.weather_tables.sunrise">Sunrise</span>
7:16
7:18
7:18
7:20
7:20
7:22
<span class="translation_missing" title="translation missing: en.weather_tables.sunset">Sunset</span>
9:01
9:00
8:59
8:58
8:55
8:53
8:52
 mm
6
6
4
6
Temp °C
20
20
21
21
19
27
24
22
30
29
27
32
24
26
26
23
24
30
24
Feels °C
20
19
19
21
17
25
25
24
29
29
28
31
25
25
25
24
25
30
24
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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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