BEIJING, June 25 (Xinhuanet) -- A rare "dry lightning" electrical storm on Tuesday generated nearly 8,000 lightning strikes that set more than 800 wildfires across Northern California.

    The weekend storm was unusual not only because it generated so many lightning strikes over a large geographical area, but also because it struck so early in the season and moved in from the Pacific Ocean. Such storms usually don't arrive until late July or August and typically form southeast of California.

    "You're looking at a pattern that's climatologically rare. We typically don't see this happen at this time of summer," said John Juskie, a science officer with the National Weather Service in Sacramento. "To see 8,000, that's way up there on the scale."

    Thousands of firefighters battled the blazes from the ground and air. No homes had been destroyed, but voluntary evacuations were in place for residents of at least 25 homes, officials said.

    Despite the many lightning strikes that hit the ground on Saturday alone, the weekend thunderstorm brought little precipitation because the rain evaporated in hot, dry layers of the atmosphere before it hit the ground, Juskie said.

    The lightning storm struck California when the state was experiencing one of its driest years on record. Earlier this month, Gov. Arnold Schwarzenegger declared a statewide drought and directed agencies to speed up water deliveries to drought-stricken areas. Many communities have adopted strict conservation measures.

    From San Francisco to Los Angeles, cities have only seen a tiny fraction of the rainfall they normally receive in a typical year. In the Central Valley, the cities of Sacramento, Modesto, Stockton and Red Bluff have recorded their driest March-to-May periods since at least the 19th century, according to the weather service.

    (Agencies)