Conditions at Aterro in May
May: Smaller Swell and the Summer North Wind Arrives
May marks the true late-spring slackening. Average wave height drops to 5-6ft (1.5-1.8m) and period to 9.8 seconds, shifting Aterro toward shorter-period swell. Directionally, NW (30.6%) and WNW (22.8%) dominate, with NNW (20.9%) also present, but the energy is less organized and less powerful than winter.
Ideal wind windows shrink to 22%, with NNW (28.5%) and NW (11.8%) now controlling the daily wind regime. Cleaner conditions come on E (3.3%) and SSW/SW (6.4%/6.0%) days, but you will need to be picky. Air temps warm to 15.9°C, water reaches 15.7°C, and rain eases to 2.40 mm/day - the calm before the summer lull.
Average Spot conditions at Aterro in May
Swell history for May
Wind history for May
Swell quality
Analyze the groundswell consistency at Aterro during May. Based on historical data, there is a % probability of groundswell occurring this month. The chart below provides a detailed breakdown of the average wave height distribution, offering deep insights into the swell quality and surf potential you can expect at Aterro for your next trip in May.
Ground swell
Ground swell by size
Wind conditions
Evaluate the wind and swell alignment at Aterro for May. Our analysis shows that favorable offshore or side-shore winds coincide with surfable swell approximately % of the time. The accompanying graph illustrates the average size distribution of waves during these optimal wind windows at Aterro.