SF is notable for having a 100-degree summer day turn into a 40-degree evening in the middle of August. There is no such thing as 'Summer' in the bay area.
I would be surprised if it's ever gotten to 100 in San Francisco. 80 is considered a hot day. If you get out of the city, it turns into summer, though. The Bay Area is famous for its microclimates. You can go 10 miles and have a 30 degree difference in temperature.
Maybe 1 or 2 days out of the year it will get to triple digits, but mostly tops out in the low 90's. Certainly much hotter in the East Bay. And you don't even have to go ten miles. I used to live in the Southwest corner of the city. I'd look out the window and see a bunch of clouds and fog. I'd get on the subway get off downtown and the sun was shining.