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Conditions at Rottnest Island in May
May: Bigger Swell and the Best Autumn Quality
May is where the winter campaign truly begins. The average swell jumps to 7ft (2.2m), the period sits at a strong 12.7s, and there is more spread in the western swell window: SW leads at 42.1%, WSW is now a major player at 16.0%, and W contributes 3.7%. The wind rose delivers the highest ideal-conditions percentage of the year so far at 15%, with offshore flow from NE (7.1%), ENE (9.4%), E (9.5%) and N/NNE becoming much more common. Onshore S/SSW flow drops to just 14.1% combined, dramatically improving surface conditions. Rains increase to 2.88 mm/day as frontal systems roll through, air temperatures cool to 18.5°C, and the water remains pleasant at 22.0°C. Long-period SW/WSW groundswell wrapping into the south-facing reefs with offshore or light variable winds makes May one of the most consistently good months of the entire year.
Average Spot conditions at Rottnest Island in May
Swell history for May
Wind history for May
Swell quality
Analyze the groundswell consistency at Rottnest Island 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 Rottnest Island for your next trip in May.
Ground swell
Ground swell by size
Wind conditions
Evaluate the wind and swell alignment at Rottnest Island 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 Rottnest Island.