The weather in the Bay Area in general is pretty pleasant, but San Francisco in particular seems to be a bit of a local minimum, with the foggy and frequently quite cold weather even in summer. As we used to remind our guests before taking them to SF: "There's a reason why there are so many tourists wearing San Francisco branded fleece jackets".

I thought about it, and AFAICT it only widens the gap between ideal weather for a homeless person and ideal weather for a non-homeless person. For a homeless person, Walnut Creek is going to be worse during the winter because it's cold, and worse during the summer because it's hot. For a non-homeless person, San Francisco is going to be worse during the June Gloom because they might be stuck in an office during the times that the sun comes out.