Warning issued as one of the longest heat waves of the year heads for Bay Area  SFGATECalifornia heat wave could dampen Fourth of July celebrations  USA TODAYWeather tracker: Scorching temperatures in California threaten heat records  The GuardianCalifornia weather: Heat wave forecast prompts warnings and advisories  San Francisco ChronicleCalifornia heat wave temperatures could top triple digits over 4th of July  Yahoo! Voices