To non-Californians: The Pacific coastal waters are freezing all the way down to San Diego. Ever been swimming off the coast of Georgia or Florida and thought, "Gosh, this isn't refreshing at all, it's like bath water." You won't have that problem on the West Coast. I grew up in New England, swimming in Maine, and it doesn't hold a candle to how frigid the waters in California can be. And the wind off the water is biting, even in August. You know how Florida's coast is developed pretty much along it's entire length on both sides, and yet California and Oregon have hundreds of miles of relatively untouched coastline? That's why. It's damn cold.
Having bodysurfed somewhere along the coast from Eugene, Oregon in the autumn, and taken several dips in Frenchmen's bay near Acadia National Park in the summer, I would respectfully disagree -- northern Maine waters are absolutely icy cold.
I have been in both, albeit in BC during fall two years past, and Newfoundland in summer eight years ago. In Newfoundland, I was purple in minutes, but in BC I was relatively okay for two hours for my lesson. So I do disagree humbly.