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 19 Aug 2026 (local time)

Forecast update in  hr  min

Today's Guethary - Les Alcyons/Avalanche sea temperature is
24.9° C
3.1° 

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 19 Aug 2026:

  • Best quality surf: Friday 21 Aug, 11PM (local time) - 5ft (1.6m), 10s period, NW swell with glassy winds.
  • Most powerful swell: Thursday 27 Aug, 2AM (local time) - 8ft (2.4m), 9s period, WNW swell with 893 kJ wave energy.
  • Next surfable swell (1★+): Thursday 20 Aug, 8PM (local time) - 4.5ft (1.3m), 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 Thursday (Aug 20) at 8PM. The primary swell is predicted to be 1.3m 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 2.4m 9s and forecast to arrive on Thursday (Aug 27) at 2AM. Winds are predicted to be glassy 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+) 8PM (Thu 20th Aug)4.5ft (1.3m) 10s
Best Surf11PM (Fri 21st Aug)5ft (1.6m) 10s
Most Powerful 2AM (Thu 27th Aug)8ft (2.4m) 9s

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


The Lowdown

Alright, this is Rusty checking in from the Basque Coast. We're looking at a strange, drawn-out forecast for Guethary - Les Alcyons/Avalanche, a proper expert reef break. The water is sitting at a very unusual `77°`, which is a solid `6°` warmer than normal for this time of year – that's a real anomaly, almost like bathwater for August.

The first week is a bit of a write-off, honestly. We've got a ton of onshore wind and messy conditions. From Wednesday the 19th through to the end of the following week, there's a lot of cross-on and onshore wind, with tiny, weak swell. The energy is mostly in the weak range, with readings like `15` and `89` – nothing to get excited about. There's a small window on Saturday morning, the 22nd, with a clean, cross-off breeze from the east and a `4 ft` swell from the northwest, but it's short period at `9 seconds` and the energy is still weak at `241`. It's surfable, but not a standout.

The end of the first week and into the second week is a big gap of poor to marginal conditions. The wind is all over the place, mostly onshore, and the swell is either too small or too messy. We finally get a promising look on Friday, the 28th of August. The morning is looking crisp with a clear sky, offshore wind from the east-southeast, and a clean `6 ft` swell from the northwest with a period of `10 seconds`. The energy is moderate at `707`, and the conditions are forecast to be very good. This is the real standout of the period – it's got the right wind, a decent size, and it's a reef break that handles the longer period well. This is where you want to be.

Then, after a few more days of small, glassy but ordinary surf, we get a bigger pulse on Monday, the 31st of August. The swell jumps to `10 ft` from the west-northwest, with a period of `10 seconds`. The energy is very strong at `1939` in the morning and `2203` in the afternoon. This is a powerful, heavy swell, but the wind is onshore or cross-on, making it choppy and marginal. That size and power make it expert-only, and the wind is not playing ball.

The real highlight for the long-range is Wednesday morning, the 2nd of September. Glassy conditions with a `7 ft` swell from the northwest, a period of `9 seconds`, and very strong energy at `720`. The forecast says "expect very good surf conditions." This is a solid, clean swell for the experts, with no wind to mess it up. It's a promising call, but we're a week and a half out, so keep an eye on it.

After that, Thursday the 3rd of September morning looks clean and glassy with a `4 ft` swell, but it's a step down in energy.

So, to wrap it up: the first week is a bust. The two true standouts are Friday morning, the 28th of August with that clean offshore wind, and Wednesday morning, the 2nd of September with the glassy conditions. Both are for the experts at this reef, but they're the best on offer.

Rusty.

Short Range Forecast

Moderate rain (total 15mm), heaviest on Thu night. Warm (max 28°C on Sat afternoon, min 15°C on Sat morning). Wind will be generally light.

Days 5-7 Weather Summary

Moderate rain (total 10mm), heaviest on Sat night. Warm (max 33°C on Mon afternoon, min 18°C on Sun morning). Wind will be generally light.

Thursday
20
Friday
21
Saturday
22
Sunday
23
Monday
24
Tuesday
25
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
1
0
1
2
2
0
1
0
0
0
0
0
0
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)
0.5
NW
13
1.3
NW
11
1.3
NW
11
1.4
NW
10
1.9
NW
10
1.7
NW
10
1.6
NW
10
1.3
NW
9
1.1
NW
9
1.1
NW
8
0.7
NW
8
0.5
NW
7
0.4
NW
7
0.4
NW
7
0.4
NNW
6
0.4
N
4
0.6
SW
4
0.5
NW
3
0.4
WNW
9
Wave Graph
Metric surfscale
Energy kJ
83
384
357
384
724
569
465
269
172
147
57
26
13
11
11
4
8
6
32
Wind (km/h)
10
W
10
W
15
NW
10
SW
15
WNW
15
WNW
5
ESE
15
E
20
NNE
15
ESE
10
E
15
N
5
WSW
10
S
25
WNW
10
S
20
WSW
15
N
10
ESE
Wind State
cross-on
cross-on
on
cross
on
on
cross-off
cross-off
cross
cross-off
cross-off
cross-on
glassy
cross-off
on
cross-off
cross
cross-on
cross-off
High Tide
9:57PM2.89m
10:21AM2.81m
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
Low Tide
4:07AM1.12m
4:39PM1.21m
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
part cloud
part cloud
thunderstorm
light rain
rain showers
rain showers
part cloud
part cloud
clear
rain showers
rain showers
clear
part cloud
part cloud
clear
part cloud
clear
part cloud
part cloud
<span class="translation_missing" title="translation missing: en.weather_tables.sunrise">Sunrise</span>
7:16
7:16
7:18
7:18
7:20
7:20
<span class="translation_missing" title="translation missing: en.weather_tables.sunset">Sunset</span>
9:04
9:01
9:00
8:59
8:58
8:55
8:53
 mm
3
5
4
3
9
1
Temp °C
22
22
21
20
20
21
21
20
28
25
22
31
30
28
33
26
25
26
22
Feels °C
24
23
21
20
19
20
20
18
25
26
23
30
30
29
31
26
22
24
21
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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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