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 pm 14 Sep 2026 (local time)

Forecast update in  hr  min

Today's Guethary - Les Alcyons/Avalanche sea temperature is
22.9°C
2.5° 

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 14 Sep 2026:

  • Best quality surf: Saturday 19 Sep, 5AM (local time) - 8ft (2.4m), 14s period, NW swell with cross-offshore winds.
  • Most powerful swell: Saturday 19 Sep, 2AM (local time) - 8ft (2.4m), 14s period, NW swell with 2,190 kJ wave energy.
  • Next surfable swell (1★+): Tuesday 15 Sep, 2AM (local time) - 3.5ft (1.0m), 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 Tuesday (Sep 15) at 2AM. The primary swell is predicted to be 1.0m and 10s period. The wind is predicted to be cross-offshore as the swell arrives.

The most powerful waves expected at Guethary - Les Alcyons/Avalanche in the next 16 days are 2.4m 14s and forecast to arrive on Saturday (Sep 19) at 2AM. Winds are predicted to be cross-shore at the time the swell arrives.

Wave TypeTime (CEST) & Date Wave Height & Period
Next good surf (1 star+) 2AM (Tue 15th Sep)3.5ft (1.0m) 10s
Best Surf 5AM (Sat 19th Sep)8ft (2.4m) 14s
Most Powerful 2AM (Sat 19th Sep)8ft (2.4m) 14s

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


The Lowdown

Alright, let’s run through this in feet and Fahrenheit.

First few days are a total bust. From Monday the 14th through Friday the 18th, it’s all choppy cross-onshore wind and tiny, weak swell. Water temp is about 73°, which is much warmer than average for this time of year, running about 5° above normal.

Things finally turn on Saturday the 19th. That morning, Guethary - Les Alcyons/Avalanche (reef break, experts only) gets a clean 7ft NW swell with a solid 13-second period, and a light offshore breeze out of the ENE. The combined energy is cranking at 1514, that’s strong to very strong. This is the standout session of the whole 16 days – powerful, lined-up waves, but only for experienced surfers. It’s a popular, consistent spot, so expect a crowd.

Sunday the 20th morning goes glassy with a 5ft NW swell, 12-second period, energy at 528. Clean and fun. Monday 21st and Tuesday 22nd mornings are also glassy with 5ft and 4ft NW swells respectively, good period. Those are your other solid windows, but Saturday morning is the big one.

After that, the swell dies. A small, glassy bump on Friday the 25th morning gives you 4ft from the NW, 12-second period, energy at 373 – rideable but ordinary. Then it’s back to tiny, weak, and cross-onshore mush until the end of the forecast on the 29th.

So for the experts, lock in Saturday the 19th morning. Sunday through Tuesday mornings are also worth a paddle. The rest is a whole lot of nothing.

Rusty.

Short Range Forecast

Light rain (total 5mm), mostly falling on Tue night. Warm (max 28°C on Mon afternoon, min 17°C on Wed night). Wind will be generally light.

Days 5-7 Weather Summary

Light rain (total 7mm), mostly falling on Fri afternoon. Warm (max 20°C on Sat afternoon, min 15°C on Sat morning). Wind will be generally light.

Mon
14
Tuesday
15
Wednesday
16
Thursday
17
Friday
18
Saturday
19
Sunday
20
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
Rating
(10 max)
1
2
0
0
0
0
0
2
2
1
1
0
1
3
4
2
3
3
0
2
Swell
Height Map
Height Map
Height Map
Height Map
Height Map
Height Map
Height Map
Height Map
Wave
Height (m)
Direction
Period (s)
1.1
NW
11
1
NW
10
0.8
NW
10
0.6
NW
9
1
WNW
5
0.8
WNW
10
1.5
NW
8
1.3
NW
9
1.7
NW
11
1.6
NW
11
1.4
NW
10
1
NW
10
1.5
NW
9
2.4
NW
14
2.1
NW
13
2
NW
13
1.6
NW
12
1.4
NW
12
1.3
NW
11
1.3
NW
11
Wave Graph
Metric surfscale
Energy kJ
286
212
133
55
51
130
264
284
663
604
388
177
359
2190
1514
1279
748
528
414
399
Wind (km/h)
10
N
5
SSW
15
W
20
W
10
NW
20
N
15
NNW
10
NNE
5
NNW
15
NW
10
W
15
WNW
15
NNW
10
NE
5
ENE
15
NNW
5
S
5
NE
10
NNW
10
SSW
Wind State
cross-on
cross-off
cross-on
cross-on
on
cross-on
on
cross
on
on
cross-on
cross-on
on
cross
cross-off
cross-on
glassy
glassy
cross-on
cross-off
High Tide
7:21PM3.72m
7:37AM3.56m
7:55PM3.45m
8:09AM3.34m
8:29PM3.14m
8:44AM3.08m
9:09PM2.84m
9:27AM2.82m
10:03PM2.57m
10:34AM2.60m
11:37PM2.40m
12:24PM2.53m
1:30AM2.46m
Low Tide
1:25AM0.30m
1:41PM0.37m
1:59AM0.57m
2:19PM0.65m
2:36AM0.87m
3:01PM0.94m
3:18AM1.17m
3:54PM1.23m
4:17AM1.42m
5:12PM1.43m
5:47AM1.55m
6:54PM1.44m
clear
clear
clear
clear
rain showers
rain showers
part cloud
rain showers
part cloud
part cloud
rain showers
light rain
rain showers
part cloud
clear
clear
clear
clear
clear
clear
<span class="translation_missing" title="translation missing: en.weather_tables.sunrise">Sunrise</span>
7:45
7:46
7:47
7:48
7:48
7:50
<span class="translation_missing" title="translation missing: en.weather_tables.sunset">Sunset</span>
8:19
8:16
8:15
8:14
8:12
8:09
8:07
 mm
1
2
2
3
2
2
Temp °C
28
24
22
22
20
19
19
18
18
19
18
18
19
18
17
20
19
18
22
20
Feels °C
26
24
20
21
20
19
17
17
18
17
17
17
18
16
16
18
19
18
20
20
  • Map Icons:
  • Break
  • 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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