Itapeva • Statistics for September

September: Spring Swell, Shifting Winds

September often produces the biggest average swell of the calendar year at 1.8m (6ft), but the wind quality begins to slip away. The average period is 9.1s, and the directional spectrum shows ENE at 18.9 percent, E at 15.7 percent, ESE at 13.9 percent, SE at 13.6 percent, SSE at 12.0 percent and S at 10.4 percent. There are more 1.5-2m and 2-2.5m pulses in this month than any other, so raw power is definitely available. However, the NE trades come back strong - NE at 25.7 percent, NNE at 14.2 percent - and the ideal wind percentage sinks to 20 percent. The onshore E, ESE, SE and SSE wind component also rises to around 12.5 percent, which can chop up the better swells. Focus on dawn patrol and days when a late-season front brings W/NW offshore flow. Water temperature climbs to 17.1°C and air averages 15.8°C.