There are a couple of near certainties about fall offshore fishing in Southern California and Mexico's northern Baja waters. The weather is usually on its best behavior, allowing even private skiffs to venture far from port in search of bait schools, temperature breaks, and the tuna associated with dolphin schools and floating kelp paddies. And there seems to be a lot less boat pressure, making it easy to get away from the crowds and on the fish, even during normally busy weekends.
What exactly might be on the offshore menu can be a little less predictable. Traditionally, albacore and bluefin reliably move into the range of one-day boats and private boats (loosely defined as 50 miles or closer) around July 4, when water temps reach the mid-60s, and then as the water warms up, they are replaced by other pelagic species, like yellowfin tuna, dorado and yellowtail. As this was written, summer 2010 had delivered a start-and-stop albacore and bluefin bite and a solid wall of cold, off-color water - referred to by skippers as the "green door" - that kept the tuna south and west of the Southern California coast. When the door opened up momentarily, boats enjoyed some epic but short-lived bites on longfins and mixed bluefin. San Diego long-range boats reported large schools of tuna down the Baja coast, which bodes well if conditions normalize and permit the usual northward migration patterns.