Weather in SF and LA is likable, but Seattle and Portland are dreadfully rain soaked and socked in clouds for 9 months of the year. You don't move to the latter two locations for the weather, you move there because they are considered trendy and "cool" in modern culture and you're a trend seeker. The same "cool" designation could be slapped onto Cleveland or Milwaukie or Ann Arbor and you'd have the same trend seekers piling into there too.