A term used by old-timers living in the coastal plain of Southern California to describe summer episodes of hot, humid weather associated with widespread middle and high cloudiness and thunderstorm activity, sometimes intense, over the mountains and deserts to the east. Summer thunderstorms, unusual over the coastal plain of southern California, occur during such episodes. Sonora weather is a particular manifestation of the Southwest monsoon, occurring when the more typical summer monsoonal flow of midlevel moisture into Arizona and New Mexico (from Sonora State, Mexico, and points south) is shunted westward.