The warning was issued at about 11 a.m. for most of the county as the weather service's radar system picked up signs of a severe thunderstorm and possible tornado approaching the coast, meteorologist Steve Anderson said.
Winds of 30 to 40 mph, a downpour of rain, and pea-sized hail were reported, but not a tornado, Anderson said.
The heavy part of the storm has passed through the Peninsula, and "once it got over the Bay, it decreased in intensity rapidly," he said.
The storm was moving through Alameda and Contra Costa counties as of 11:40 a.m., he said.
