Cave Rock • Statistics for May

May: Winter's First Surge

May is when the Southern Ocean engine fully kicks into gear. The average swell height remains steady at 1.7m (5.6ft), but the average period stretches to 10.4s - a strong mid-period groundswell signal. The wind stats are the big story: ideal offshore flow jumps to an excellent 49% of the time. The wind rose shows a dramatic increase in N-NW flow, with NNW at 10.5%, NW at 4.6%, WNW at 3.8%, and W at 3.2%. A corresponding drop in NE winds (now 13.5%) means fewer onshore days. The swell direction shifts to the south and southeast: S now dominates with 21.9%, SSE 19.0%, and SE 15.6%, while the pure E component fades to 15.2%. The 1.5-2m and 2-2.5m bands are packed with energy, especially from the S and SSE sectors. Water temp is a crisp 23.7°C, air 22.2°C, and rainfall falls to a dry 1.33mm/day. This is when Cave Rock starts to look like a proper winter wave - clean walls, consistent overhead sets, and offshore breeze grooming every face.