Question submitted by Dave Seminchuk
Hi there Dave,
Welcome back to "cloudy ol' BC"!! Good question. Now part of the answer purely is perception. San Francisco is actually a rather foggy/cloudy city, thanks to the warm air from inland (where it gets quite hot in the summer) clashing with the cold air coming across from the surrounding Pacific Ocean and the SF Bay. When that happens, fog forms. But that's a rather local effect.
But in a more general context, BC's coastline is cloudier due in part, to the path of the jet stream. This ribbon of fast moving air aloft, carries with it weather systems (more specifically cloud bearing weather systems). Due to the latitude of Canada and the tilt of the Earth, we lie in a more temperate zone.. and the jet stream tends to feed these systems along our coastline for longer periods of time. Hence, on average, we end up with cloudier conditions for greater periods of time in the year than they do in, say, California.