High pressure aloft over California and Nevada will slowly weaken with slow cooling through Thursday.
Upper level low pressure over northern Baja will draw some mid level moisture into far southern California with a slight chance of showers and thunderstorms... mainly for the mountains... deserts... and inland valleys.
For Friday through Monday... a low pressure system moving inland through the western states will bring a return of onshore flow with cooling to near to slightly below seasonal temperatures... gusty west winds in the mountains and deserts... and a return and deepening of the marine layer with night and morning coastal low clouds and patchy fog extending farther into the valleys by Sunday and Monday.
United States WX Overview...
Cold fron approaching the East Coast with numerous showers and storms expected.
Cool and dry for much of the central plains and Rockies.
Drought in Southern California climaxed and hot Santa Ana winds blew starting on 9/25 and ending on 9/30. Winds peaked at 60 mph at Cuyamaca. The winds sparked the Laguna Fire, one of the largest in California history. Eight were killed, 400 homes were destroyed, and 185,000 acres were burned as of 9/28 from Cuyamaca to Alpine. In all, the fire consumed whole communities of interior San Diego County. Half a million acres were burned and caused fifty million dollars in damage.