During the warm season, the subtleties of local weather are to be savored, and none is more frequent than the Sound Breeze.
Official definition: the Sound Breeze is the northerly wind that develops during the midafternoon over the northern half of Puget Sound and which maintains itself until approximately 8-9PM. Over the central Sound the breeze can blow 15-20 knots, with less winds over land.
The sound breeze is important for everyone like to sail, fly kites, or bike home after work. Many an afternoon I have to bike right into it...slowing me down considerably. And it makes kite flying wonderful during the late afternoon at kites hills at Magnusson or Gas Work parks. And it is heaven for early evening sailors.
The Sound Breeze is really a big sea breeze circulation. Remember the sea breeze? Cool, ocean air moving towards the heated land during the day? In this case, we have the Strait of Juan de Fuca and Georgia Strait full of water and the Puget Sound basin mainly land. As the PS basin heats, the pressure falls and the northerly sea breezes pushes in.
Above are two maps of surface winds on May 23...one early in the day and the other at 4 PM. You can see a real strengthening of the northerly flow in time..the Sound Breeze in action.