Mejillones seasonal overview
Best Surf Season (December - March)
Winter is when Mejillones truly turns on. The North Atlantic storm track sinks south and fires long-period swell into the northern Spanish coast, and this NNW-facing beach is beautifully positioned to catch it. The data shows average swell heights of 2.1-2.2m (7ft) and average periods of 12.0-12.9s, with a heavy concentration of swell from the NNW, NW and N quadrants. During these months the swell is powerful and well organized, and although the prevailing NE wind still limits the glassy windows, December stands out with 23 percent ideal wind, while January offers 19 percent. When high pressure drifts over Iberia and winds slip into the S/SSW/SW/WSW quadrant, Mejillones lights up with hollow, long-period lines.
Fair Surf Season (October - November and April)
The shoulder months act as a bridge between regimes. October and November see average heights jump to 1.7m (5-6ft) and 2.0m (6-7ft) and average periods rebuild to 11.4-11.9s as the first major North Atlantic lows organize themselves. The swell direction remains predominantly NNW/NW, so the exposure is still working, but the wind statistics show NNE/NE still dominating. April is fair but fragile: average swell is still 1.9m (6ft) and periods hold at 10.9s, yet ideal wind drops to just 5 percent, meaning many solid swell days are marred by onshore texture. These months reward patience-the best session window often comes in the early morning before the NE seabreeze kicks in.
Low Surf Season (May - September)
From May to September, the Azores High muscles in and the North Atlantic storm track retreats. Average periods collapse to 7.7-10s, average heights drop to 1.4-1.6m (4-5ft), and the wind regime becomes relentlessly NNE or NE. At Mejillones these winds are onshore to cross-onshore, so ideal surf wind drops to 2 percent or less from June through August. The good news is the beach still sees NNW and N windswell almost every day; the bad news is that it is usually short-period, bumpy and without the long-period push needed to make this exposed spot really firing. Summer is not the time for quality-it is a small-wave, grovelly trade wind period with only occasional fun peaks.