bottom line is so cal beach swimming is good from May-Sept. with some very nice days in the other months that you can choose at your own discretion, but you probably won't be swimming in the ocean. the navy seals train at Coronado bay near San Diego and they freeze there a$$ off and many of them suffer from hypothermia from being in the water too long during the winter months and even fall. granted they're in the ocean a lot longer than you will be, but the point is 55 degree water is not tourist or leisure-time swimming water. it's for navy seals and surfers with wet suits. stick to the summer.