The California Highway Patrol reports at least 10 weather-related accidents in Sonoma County so far Tuesday morning, though none with major injuries or damage.
Several accidents were single-vehicle spinouts, Officer Kimberly Lemons said, but several were chain-reaction rear-end collisions involving three or more vehicles, suggesting drivers were driving too fast and following too closely on the rain-slick roads.
Police were particularly busy on the usual trouble spots - the Highway 101-Highway 12 connector ramps and the windy switchbacks of Calistoga Road west of St. Helena Road.
The tight turns and banked curves are "like the spin cycle of a washing machine," she said, and drivers were finding it difficult to maintain control.
Weather forecasters expect rain through tomorrow, accumulating as much as an inch in some areas. Lemons advised motorists to slow down and leave extra following distance on all roads, particularly anywhere with curves or banked turns.