If we're going by anecdotes... when I came to this city I was told thick blinding fog is a daily occurrence, but I was here a good week or two before the "real" fog came in, and while fog does come often, that honestly doesn't come often. Maybe 3 times a week.

I classify "real" fog as days where I go from being able to see half of SF and even a bit of Alameda... to not seeing the houses a block down from my balcony.

I'll admit it's impressive and straight up disorienting sometimes, (looking out at what was a skyline 20 minutes before and seeing nothing but grey), but if the locals' anecdotes about how often it used to happen are even somewhat accurate, it sounds like it's on the decline.

It's not daily- there is more like a cycle caused by changes in offshore flow and temps in the inland valleys. I'd see a week without any fog, then a two weeks of in-and-out fog, then a week of total fog, including times when I couldn't see more than a few avenues towards sunset, or the park looked like some misty dream.

Concur: I spent perhaps 10 days in the city in 1995 split into two blocks at end of June and beginning of September. Definitely foggy on multiple days, especially over towards Golden Gate Park and the bridge.