San Francisco also benefits from the contrast between the cold ocean current and the extreme heat of California’s Central Valley. The result is a pretty steady onshore flow of cool air, pulled in by the stifling hot air inland which rises.

What's the hottest it's ever been in San Francisco?

The hottest it’s ever been in SF was 103 degrees which occurred on June 14, 2000 and July 17, 1988.

Is SF getting warmer?

For example, in 1970 the average low for San Francisco was a little over 53 degrees across summer months. … By 2018, that figure was up to a little over 56 degrees.