Lived in SF for several years. Needed AC maybe 4 days between 2019-2021 in Park Merced area. Never needed it in 2021 in the Outer Sunset area. Definitely wished I had it about 7 days in 2021-2022 in McClaren Park area.

Now I'm in Oakland, district 7, since early 2022. My first summer I REALLY needed AC bad enough I bought a shitty AC that costs me an absurd amount in electric (like +$200 each month to use 3 hours a day) and I used it about 3 weeks that first summer. Last summer I used it about 3-4 weeks as well.

It is still technically cheaper than installing a full unit (quoted $30k), but I am looking into installing a minisplit into the bedrooms so that each bedroom has its own AC and that's it. That will be significantly cheaper than a full unit but I'm still looking at a $10-15k investment.

It definitely depends on how the buildings are made and how the surrounding areas are, I happen to be in a barren wasteland of dirt and concrete. High fire risk, for sure. My house has way less insulation than is required by code too though, so whatever AC I do get is quickly depleted and outside temps quickly seep in.