Gosh! Correct me if I'm wrong, but I remember summers in the Avenues always being foggy!! This is why my family, and many other families, would head to Marin or Sonoma County, or the Russian River resorts to have vacation or weekend breaks from the damp and the fog. And, my folks had a little cabin in San Mateo County (Los Trancos Woods) where we would, many times, spend most of July and August. (Dad would stay in the City for his job, and come down on weekends.) So, no, I don't think this is a new weather phenomenon.