Bay Area’s first 'real’ rain of season expected Wednesday

This NOAA satellite image taken Tuesday, Sept. 23, 2014 shows a large ocean storm over the Pacific. That is moving some showers into the Pacific Northwest and the Bay Area by Wednesday night.

This NOAA satellite image taken Tuesday, Sept. 23, 2014 shows a large ocean storm over the Pacific. That is moving some showers into the Pacific Northwest and the Bay Area by Wednesday night. Photo: Noaa, Associated Press Photo: Noaa, Associated Press Image 1 of / 4 Caption Close Bay Area’s first 'real’ rain of season expected Wednesday 1 / 4 Back to Gallery

The unfamiliar sight of rain is expected to gloss Bay Area skies late Wednesday and early Thursday, marking what could be the first significant rainfall in the region since spring.

Forecasters say a front from the Gulf of Alaska could bring a tenth of inch of rain to lower elevations and a quarter inch or more to hills in Napa and Sonoma counties as well as the Santa Cruz Mountains.

Commuters are being warned of a possible sloppy commute Thursday morning after overnight moisture douses Bay Area roads.

“This is the real deal. It’ll be rain. Not just the light stuff and drizzle that we’ve seen some days,” said National Weather Service forecaster Steve Anderson, noting that this could mark the start of California’s rainy season. “We typically see our first rain event at the end of October. This is a few weeks early but it’s not unheard of.”

The storm is also expected to bring rain to mountainous parts of the state where wildfires have roared amid warm weather and extremely dry conditions. The moisture will be welcomed by firefighters battling the 89,574-acre King Fire in the central Sierra and the 131,996-acre Happy Camp Complex along the Oregon border.

“They’ll get some relief up there,” Anderson said.

The wet weather comes as California reels from three abnormally dry years.

This week’s storm is expected to be short-lived, however, with sunny skies and normal temperatures in the upper 60s and early 70s returning to the Bay Area by Friday.

Kurtis Alexander is a San Francisco Chronicle staff writer. E-mail: kalexander@sfchronicle.com