It can be still cold in February but it is a hell of a lot warmer than NY.
In SoCal, the water temp will be anywhere from 54 - 62 degrees. A 6/4 will keep you warm for sure but it is really over kill out here. My 5/3 is perfect. Some guys have some big ones out here and do the spring suit...
The swell here was insane... from San Diego area (where I am) all the way up the coast. We had 15 footers at some breaks which only made it more insane. I got out one day was in the water for about 1/2 hour. Caught two waves but it took forever to get back out in the line up.