Thunderstorms that were expected to bring the kind of lightning that lit up skies Monday and Tuesday morning off the coast of Half Moon Bay never materialized in the Bay Area, said Diana Henderson, a meteorologist for the National Weather Service. Not a single ground-to-air lightning strike took place in Santa Clara, Alameda, San Mateo or Contra Costa counties, she said.

"The lightning activity (Tuesday) was mostly over the ocean in the North Bay and in the Sierra Nevada," she said. "And the only conductive activity (Wednesday) is going to be anywhere from Marin County and north, and again in the Sierra."

Fire crews in the region have been on high alert since midnight Monday in anticipation of dry lightning strikes, and the red flag warning remains in effect until 3 a.m. Thursday, Henderson said.

The East Bay saw two blazes Tuesday, but neither was sparked by lightning.

In Martinez, off Highway 4 near Franklin Canyon Road, a car fire at 9:30 p.m. spread to some grass and burned about 2 acres, Cal Fire Battalion Chief Brandon Leitzte ¿said.

In Dublin, a smoke grenade used in a military training exercise sparked a 170-acre brush fire at 1:40 p.m. that could be seen for miles around Camp Parks on Tuesday afternoon, officials said.

Nobody was injured and no structures were damaged in the two blazes.

The threat of fires in the Bay Area should be reduced further by the weekend, when a high pressure system pushes out the moist air, Henderson said. Cooler temperatures are expected by Saturday, she said.

Dan Berlant, spokesman with the California Department of Forestry and Fire Protection, said his crews are aiding crews with about a dozen wild fires throughout the state, the biggest of them centered in the Stanislaus National Forest, just east of Yosemite National Park. A fire there has burned more than 16,000 acres.

Contact Rick Hurd at 925-945-4789, and follow him at Twitter.com/3rderh.