Mark Twain did say, "Nobody ever wears Summer clothing. You wear black broadcloth--if you have it--in August and January, just the same. It is no colder, and no warmer, in the one month than the other. You do not use overcoats and you do not use fans. It is as pleasant a climate as could well be contrived, take it all around, and is doubtless the most unvarying in the whole world. The wind blows there a good deal in the summer months, but then you can go over to Oakland, if you choose--three or four miles away--it does not blow there."
So here is my unsolicited annual advice to those of you who plan on visiting San Francisco between June and August.
If you don't believe me, you may end up in Fisherman's Wharf buying one of these...