Guethary seasonal overview
Best Surf Season (October - March)
Guethary points nearly square into the North Atlantic, and between October and March the storm track becomes the main character. Frequent cyclones rolling east across the Atlantic generate WNW, NW and NNW groundswell with periods of 12-13s, and the average swell height runs 5-6ft (1.5-1.8m). The NAO acts as a seasonal metronome: negative phases often pin the low-pressure track over the Bay of Biscay and feed Guethary with direct, long-period WNW/NW energy, while positive phases can shift the action north - but there is almost always enough groundswell to keep the banks working. With SSW, SW, WSW and W winds supplying the offshore component 35-50% of the time, this is the prime window for world-class, hollow beach peaks.
Fair Surf Season (April - May & September)
The fair season is a story of transition. April and May see the winter jet retreat, average wave heights drop to 3-4ft (0.9-1.2m), periods fall below 11s, and the northerly winds become more common. The swell direction remains in the ideal WNW/NW window, but you have to work harder for clean conditions. September is the opposite: the Atlantic begins to stir again and the first long-period swells of autumn arrive while the water is still warm from summer. The window is inconsistent, but it can produce some of the most enjoyable surf of the year.
Low Surf Season (June - August)
Summer is the low season at Guethary. The Azores High bulges across the Bay of Biscay, pushing the Atlantic storm track far to the north and leaving the coast with mostly short-period NW windswell. Average wave heights slump to 3ft (0.9m), periods sit around 9s, and the N/NW wind sector dominates, providing ideal wind only 15-19% of the time. Small, lumpy and often wind-affected days are the norm, although early-morning sessions and occasional longer-period pulses can still make the summer worthwhile for forgiving surfers.