Johanna seasonal overview
Best Surf Season (May - September)
The Southern Ocean fires on all cylinders from May through September, delivering Johanna's most consistent and powerful swell. Average wave heights climb to the 2.6-2.9m range with periods hovering around 13 seconds – that's long period, groundswell territory. The dominant SW and WSW energy slams straight into this SSW-facing beach, producing hollow, rippable walls. Winter's strong frontal systems and deep low-pressure cells spinning up near Antarctica are the driving force. Offshore winds from the N, NNE, and NE occur roughly 30-35% of the time, often aligning with post-frontal high-pressure ridges. When it all comes together, you get pumping, firing surf with clean, offshore texture.
Fair Surf Season (April & October)
April and October serve as transitional windows where the swell quality remains high but consistency and wind reliability take a small step back. April still pumps out an average 2.5m swell at 12.7s, with a solid 33% offshore wind score – one of the best wind percentages of the year. October sees the swell start to wind down (2.7m, 12.6s) and the offshore wind window drops to 25%, but the predominant SW/WSW swell still offers plenty of fun, solid waves. These months can dish out epic days when a late-season storm aligns with a northerly breeze.
Low Surf Season (November - March)
The summer months from November through March bring the smallest average surf of the year (2.3-2.4m, 11.7-12.0s), though even these numbers are respectable by many standards. The real issue is the dominance of onshore winds from the S, SW, and WSW – the same directions that bring the swell – which create bumpy, chop-ridden conditions. Ideal offshore wind percentages drop to 22-25%. The swell still rolls in from the SW and WSW, but periods are shorter and the wave heights often sit in the 1-2m fun-size range. It's not a write-off: early mornings or days with a strong inland heat trough can produce brief offshore windows, but overall consistency and quality take a seasonal dip.
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Conditions at Johanna in August
August: Still Pumping
August holds steady as the second biggest month of the year. Average swell height peaks at 2.9m and period at 13.2s – the highest of any month. The swell is again dominated by WSW (16.5%) and SW (12.6%), with WSW gaining an edge. This is prime time for long-period, powerful groundswell that jacks up on the outer reef. Ideal offshore wind falls to 28%, and the wind rose shows a strong component of W (11%) and WNW (12%) winds, which are onshore and can ruin the shape. Yet the frequency of N and NNW winds is still high (24% combined). The key is to target the tail end of a front, when the wind swings behind and comes from the N or NW before clocking back to the W. When the conditions line up, August offers epic, hollow, firing surf.
Average Spot conditions at Johanna in August
Swell history for August
Wind history for August
Swell quality
Analyze the groundswell consistency at Johanna during August. 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 Johanna for your next trip in August.
Ground swell
Ground swell by size
Wind conditions
Evaluate the wind and swell alignment at Johanna for August. 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 Johanna.
