SAN FRANCISCO (KCBS) -- Those loud booms you may have heard outside your window Friday night were not a dream.
A dry lightning and thunderstorm system moved through the Bay, causing several grass fires and power outages throughout San Francisco.
The National Weather Service has issued a red flag warning, mainly for the northern Bay Area counties through 5 p.m. Saturday.
KCBS' Mark Seelig Reports
As of Saturday morning, more than 35,000 customers in San Francisco were affected by outages, although many have been restored.
Those affected included people in the Excelsior District, Sunset, Parkside, Outer Mission, Laurel Heights, St. Francis Woods, Glen Park, Haight Ashbury and Hayes Valley neighborhoods.
CalFire also reported a number of small grass fires in Sonoma, Alameda and Santa Clara counties.
Officials said most of the fires seemed to have been caused by overnight lightning strikes.
(kmi)