Gunnamatta • Statistics for September

September: Longest Periods and a Shift Back to SW

September is the bridge from winter to spring and brings the longest average wave period of the year at 12.9s. Average swell height stays high at 5.5ft (1.7m), but the extra period adds real speed and power. The direction mix swings back toward the southwest, with SW at 45.1% and WSW at 21.0%; total favorable SSW through W swell is around 79%. The 5-6.5ft (1.5-2m) class is very well represented from both SW and WSW, and there is a consistent supply of 6.5-8ft (2-2.5m) groundswell as well.

Wind conditions improve only slightly. Ideal offshore wind is at 16%, and the violent NNW of midwinter is easing to 12.9%, though WNW, W, WSW and NW still provide frequent cross and onshore energy. The best days are when a high pressure ridge sets up over the Tasman Sea and produces multiple days of light E/NE offshore flow. Water temperature is still cold at 13.1°C, air averages 12.3°C, and rainfall remains high at 2.43mm/day. It is worth chasing-this month can deliver world-class beach break waves.