National Weather Service says "turn around if you encounter flooded roads. Most flood deaths occur in vehicles."
They also urge travelers to use extra caution at night, when it is harder to recognize the dangers of flooding.
Here is the weather forecast from National Weather Service during the Flood Watch:
Heavy rain through early Saturday morning
across much of the north coast region and small stream
and urban flooding in many areas in Mendocino County.
There is a slightly enhanced potential for debris flow in the Redwood Valley
Burn Scar area, where rainfall is heaviest.
Rainfall accumulations of up to 4 inches are expected, with hourly rainfall rates reaching .5 inches per hour at times overnight Friday. Total rainfall amounts will likely range from 5 to 7 inches across a broad areas.
Some locations that will experience flooding include: Ukiah, Fort Bragg, Willits, Point Arena, Covelo, Laytonville, Albion, Leggett, Boonville, Philo, Hopland, Potter Valley, Gualala,Rockport, Piercy, Talmage, Calpella, Branscomb and Navarro.