What makes the Bay Area unique is its microclimate system. At the height of summer, it can be eighty-degrees on sunny Stinson Beach and hovering in the mid-fifties less than a dozen miles south at Ocean Beach. If you are determined to have sun with your beach, stick to Marin and Point Reyes to the north and Half-Moon Bay and the Santa Cruz area to the south. If you happen to be visiting in July and August, the "winter" for much of San Francisco because of the fog, you might have to drive for a bit to find the sun. Luckily, all drives in every direction from San Francisco are beautiful.
But don't cross off those local San Francisco beaches just because of a little foggy weather. Remember: fog is not poison gas. In fact, in this day and age of worrying about health and avoiding pollution, fog offers the coolest and freshest air around. If you're traveling from most of the nation during the hotter months of the year, just consider that blasting fog at Ocean Beach or Ft. Funston our Bay Area version of free and natural air conditioning.
Whether you're looking for fog or sun, though, this list has the best beach for you.