Wet weather brought a slow start to the morning commute on Highway 101 Wednesday.
A three-car collision at South Petaluma Boulevard backed up southbound traffic through Petaluma around 6:30 a.m., the CHP said.
Another vehicle spun out on the wet highway and slowed traffic at San Antonio Road near the Marin County line, according to the CHP.
Parts of Sonoma County received .5 to .75 inch of rain overnight, according to Steve Anderson, a forecaster with the National Weather Service, and moderate rain fell in the early morning hours just before dawn.
Anderson said North Coast residents could see showers throughout the day Wednesday with possible clearing Thursday morning.
More rain is expected on Friday and through the weekend, he said. The weekend storm could bring up to an inch of rain, he said.