Rain that was pounding counties up north is now starting to drench San Diego.
A flash flood watch will be in effect for county coastal areas and valleys from 4 a.m. through this afternoon.
Heavy rain could bring debris flows in recently burned areas.
Rain is likely to continue into Tuesday with 1 to 3 inches predicted in the coastal basins, 2 to 4 inches in the mountains and up to 0.5 inch in the deserts, according to the NWS.
There is also a wind advisory in effect from 7 a.m. to 4 p.m.
Snow accumulation of 1 to 3 inches is expected in the mountains tonight, with the snow level lowering to 4500 feet.
Forecasters warned motorists to slow down and use extra caution when driving on rain-slicked roads. Blowing snow and dense fog will likely make driving hazardous at times for those traveling in the mountains.