Are there any good beaches near San Francisco? Is the water warm enough to swim in July or is it too cold?

The water is NEVER warm enough to swim in in Northern California. For good beaches (where the brave and the young do actually go into the water) try Santa Cruz and Capitola.

Stinson Beach is beautiful but water very cold. Even in Santa Cruz, if you do out far enough to actually swim, it's cold. Carmel City Beach is beautiful and slightly warmer because it's in a small cove.

I like Ocean beach in the city itself but some would say that its dirty and overcrowded and oh yeah, a lot of people drown cause its the tides are dangerous. But it beats not having a oceanfront beach

I'd second the Monterrey beach. I went so far as to stick my toe in the water, and it wasn't bad. But even if you don't go in the water, it's a nice beach to relax on.

A new beach which I think is absolutly wonderful is the beach at Crissy Field. The beach is a bit protected, so you will find kids playing in the water in spite of the temperature. As other posters have pointed out, the water in Northern California is never warm enough for a casual swim - although I have been known to jump in just to say I have.