Known for its mild, sunny climate, Southern California has been in the grip of a heat wave over the past week. Coming on the heels of a cool summer, this heat wave culminated in an all-time record high of 113 degrees F yesterday afternoon; of course, this record is based on modern human experience and may have been eclipsed thousands of times in the past.
Southern California's mild climate is due, in part, to a northerly current along the west coast of North America, which brings cool ocean water from the northern Pacific. This current is an extension of the Japanese Current which, like the Gulf Stream of the Atlantic, transfers warm water to the north and east, moderating weather conditions across southeastern Alaska and British Columbia.
This past week, a ridge of high pressure over the Great Basin and Southwest has blocked any onshore flow of cool, marine air; in addition, this dome has squelched cloud formation, allowing the region to bake in the early autumn sun. Finally, an easterly breeze across Southern California, downsloping from the high desert and mountains to the east of the L.A. Basin, enhanced the heat at the surface, resulting in a new record for the City of Angels.
