San Onofre State Beach • Statistics for October

October: The Fall Transition Arrives

October is when San Onofre starts to wake up. The average swell height sits at 3ft (0.9m), but the period is a strong 13.4s, and the direction remains locked into the favorable southwest window: SW 40%, WSW 36%, SSW 9%, and W 14%. The dominant wave heights are still in the 2-3ft (0.5-1m) range, but a solid 15% falls in the 3-5ft (1-1.5m) bracket, with a few 5-7ft (1.5-2m) pulses. As the North Pacific storm track begins to spin up, the background southwest energy will slowly expand into more classic fall groundswell.

Wind quality improves markedly. Ideal wind frequency jumps to 30%, with the offshore N-NE quadrant contributing over 12% of observations and NW winds adding another 8%. The onshore S-WSW flow drops to about 32%. This creates genuine glassy dawn windows and occasional all-day offshore days. Water temperature is still warm at 17.5°C, air temperatures average 19.6°C, and rainfall is modest at 0.47 mm/day. October is a month of transition - when the first real NW groundswell and NE offshore wind line up, it is a sneak preview of winter.