Pistil said:Well darn, I think we all know Seattle and San Francisco are pretty different ...
True. I read some criticism of the Koppen system that said it lumped together too many different climates under each three-letter zone. It wasn't specific enough for some uses.
I'm sure that's true, even though some counties in the USA have three or more
different Koppen zones inside them! Maybe that's often an effect of elevation, especially when there are weather stations reporting data for the different elevations or North/South exposures.
It looks to me as if Sunset Zones go for precision rather than generality, and they also use map-location to specify a Zone.
San Francisco looks like Sunset Zone 17:
"Marine effects in Southern Oregon, Northern and Central California",
I guess foggier and a little warmer in winter than Seattle, which is
Sunset ZONE 5:
"Marine influence along the Northwest coast, Puget Sound, and South Vancouver Island"