13th Beach • Statistics for May

May: Peak Offshore Wind and Winter Groundswell

May is arguably the most consistent month of the year at 13th Beach. Average swell height holds at 5-6ft (1.6m), the period is a strong 12.4s, and the wind data shows the highest percentage of ideal surfing conditions of any month: 29%. Offshore flow from the N, NNE, NE and NNW peaks at about 30% of the wind rose, while onshore SSW and SW winds drop to just 19.5%. This is the classic late-autumn pattern - cold fronts tracking eastward under the polar front, preceded by northwesterly winds that groom the surface before each new SW groundswell arrives. Swell direction is dominated by SW (42%) and SSW (16%), with a significant 14% from WSW as frontal swells swing slightly further west. Wave heights are highly surfable, with plenty of 3-5ft (1-1.5m) and 5-6.5ft (1.5-2m) waves, plus a growing number of 6.5-8ft (2-2.5m) sets. Water temp dips to 14.5°C and air averages 13.8°C, but the quality far outweighs the chill. If you want reliable, powerful, well-groomed beachbreak waves, May is a prime month.