A lot of people think San Francisco = California = L.A., and that couldn't be further from the truth. Beachfront property comes at a discount by comparison (given that the ocean currents pass through Alaska on this side of Santa Barbara, versus the beach set in L.A./San Diego with more tropical currents).
We're just in our typical summer weather pattern where the Central Valley (Sacramento, etc.) heats up to 38-degrees-plus, creating a sort of heat pump that draws in the cold ocean air over SF and leaving cool fog banks in its wake. It's natural air conditioning, and I love it. A lot of others aren't so thrilled with it.
But come September/October when the Central Valley cools a little, the heat pump effect dies out and it warms up nicely here.