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Conditions at Rottnest Island in July
July: Peak Winter and Maximum Swell
July is statistically the biggest-swell month of the year, with an average height of 9ft (2.7m) and an average period of 13.0s. The swell window is dominated by SW (26.0%) and WSW (16.5%), with a healthy scattering of W and NW energy that keeps the Southern Ocean machine well fed. The wind pattern remains excellent by Rottnest standards: ideal conditions hit 16%, with NNW the leading offshore direction at 8.1%, followed by strong showings from NE (7.5%), E (6.7%) and N/NNE. Onshore S/SSW is a minor feature at 8.7% combined. However, westerly winds are also brisk - W, WSW and WNW combined make up over 22%, with 20-50kph winds common - so surface conditions can turn quickly when fronts pass. When the wind cleans up to offshore, the south-facing reefs see some of the heaviest, most powerful surf of the year. Air temperatures bottom out at 15.7°C, rain is at its wettest with 4.53 mm/day, and the water drops to 20.0°C.
Average Spot conditions at Rottnest Island in July
Swell history for July
Wind history for July
Swell quality
Analyze the groundswell consistency at Rottnest Island during July. 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 July.
Ground swell
Ground swell by size
Wind conditions
Evaluate the wind and swell alignment at Rottnest Island for July. 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.