Update noon Friday, Aug. 7: The National Weather Service reports nearly 1,000 lightning strikes zapped the greater Bay Area overnight in a fairly uncommon dry thunderstorm system that generated a wildfire warning for a large swath of Central and Northern California.
The majority of the strikes hit the Southern Bay Area between 8 p.m. Thursday and midnight, NWS San Francisco/Monterey Bay Area Forecaster Steve Anderson said.
A red flag, or fire weather warning, remains in effect for the Sierra Nevada foothills and northeastern California.
Lightning sparked five small fires in Monterey County, Cal Fire spokesman Daniel Berlant said Friday morning. Firefighters were able to contain them overnight, he said.
Cal Fire still reports 22 active wildfires throughout the state. Firefighters slightly advanced containment overnight of the Rocky Fire -- the state's largest fire burning in Lake County, about 100 miles north of San Francisco. The blaze is more than twice the area of San Francisco, and is now 45 percent contained.