Dry Thunderstorms Could Accelerate the California Wildfires

With wildfires burning almost one million acres of California, storms may sound like needed relief. But the dry thunderstorms projected to arrive as early as Sunday morning are the worst of both worlds.

“You still get all the lightning, but you don’t get any of the rain,” said Drew Peterson, a meteorologist with the National Weather Service in the San Francisco Bay Area.

Dry thunderstorms have an elevated cloud base, so the precipitation that falls quickly evaporates in the dry air below, Mr. Peterson said. Even if lightning does not set new fires, erratic winds can send current fires in unexpected directions.

Because of the possibility of storms, the National Weather Service issued a red flag warning from Sunday morning until Monday night for the entire Bay Area and Central Coast; it also announced a red flag warning from Sacramento up to Lassen County.