Thurso East • Statistics for September

September: The Autumn Transition Fires Up

September is where things get serious again. Average swell height jumps to 1.3m (4.5ft), but more important is the period: 9.8s and rising. Early-autumn extratropical lows are already spinning up in the North Atlantic, firing long-period energy towards the Scottish coast. The direction distribution is prime Thurso East - WNW leads with 22.6%, followed by W 16.5%, NNW 15.2% and NW 12.7%; together the N, NNE, NW and NNW sector accounts for 32.3% of all swell directions. Sections of the 1.5-2m and 2-2.5m columns begin to fill in again, particularly from W and WNW.

Wind quality remains decent: ideal offshore flow is at 33%, and the SE/SSE/S group is well represented (9.6%, 9.5%, 8.9%). Water temp is still comfortable at 13.4°C (56°F), though air temps cool to 11.8°C (53°F) and rainfall averages 3.04 mm/day. September is a transition month - but for those who can read the synoptics, it often delivers the first true world-class swell of the new season.