Conditions at Thorli in September
September: Autumn's First Swell
September is where Thorli begins to transform. The average swell height climbs to 6-7ft (2.1m) and the period extends back to 9.4 seconds as the first strong autumn lows march across the North Atlantic. Ideal offshore wind still covers 24 percent of the month, giving a decent chance at clean conditions. The wind rose is split: NNE (8.5%), NNW (10.2%) and SE (8.2%) all have their moments, but the strong westerly flow from the developing Icelandic low is not yet dominant. The favorable swell window contributes about 11 percent of the wave rose, with SE (6.9%) and ESE (2.8%) leading. More importantly, the average height is increasing and the period is getting longer, so those southeast pulses start to carry more punch. SW swell (16.2%) is already building, but it still needs a west/northwest offshore wind or a shift into the east quadrant to light up Thorli. Air temps cool to 7.4°C, water remains warm at 10.3°C, and rainfall increases to 5.57 mm/day. September is the sweet spot for catching the first real surf of autumn before the wind turns ugly.
Average Spot conditions at Thorli in September
Swell history for September
Wind history for September
Swell quality
Analyze the groundswell consistency at Thorli during September. 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 Thorli for your next trip in September.
Ground swell
Ground swell by size
Wind conditions
Evaluate the wind and swell alignment at Thorli for September. 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 Thorli.