Update: 12:45 p.m. Wednesday:

The growing and destructive Loma Fire continued moving toward remote California homes in the Santa Cruz Mountains on Wednesday as it scorched its way through bone-dry brush and trees.

The fire, burning in steep mountain terrain south of San Francisco, grew overnight to over 2,200 acres and is only 10 percent contained, according to Cal Fire. It gutted one home and threatened 300 buildings, though it was not clear how many were homes or smaller structures.

Authorities ordered residents of several canyons and other rugged areas to evacuate.

Cooler temperatures and calmer winds were expected to help more than 1,000 firefighters battling the flames, said Capt. Nick Wallingford of the Cal Fire.

"The cooling trend is very good news, but there's still a big threat," he said Wednesday. "Today, we're really going on the offensive in fighting this fire."

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The fire burned in an area dotted with large-scale marijuana growing operations. Anthony Lopez returned Tuesday to check on his home, which was still under an evacuation order, and was overjoyed to find dozens of his marijuana plants intact and his 1972 Buick Skylark uncharred.

Norman Noble, 75, left the mountain home where he's lived for a quarter-century as flames approached and fire trucks rolled in.

"I evacuated ... because I didn't want to get in anyone's way," he told the San Jose Mercury News, adding that he had no idea when he might be able to go back.

The fire started Monday during a heat wave that brought low humidity and temperatures in the upper 90s to much of California. The heat began easing, but fire risk remained extreme.

Update: 11:42 a.m. Tuesday:

The Loma Fire has now spread over 2,000 acres, and more than 500 fire personnel are now fighting it.

The blaze has so far destroyed one home and charred more than 1.5 square miles of dry brush and timber, according to Cal Fire. The fire is only 5 percent contained.

"The fire right now is very active," said Cal Fire Battalion Chief Jonathon Cox. "There's a lot of dry fuel up there and heat that, combined, are pushing this fire in directions at a rapid rate of spread or critical, as what we refer to it as."

Evacuation centers have been set up at Soquel High School, the Jewish Community Center of Silicon Valley in Los Gatos and Morgan Hill Presbyterian Church.

Original Post:

CLOVERDALE -- A fast-moving wildfire prompted the evacuations of 300 homes in the Santa Cruz Mountains, while fire crews continued to battle a blaze burning close to a massive geothermal power-producing facility in Sonoma County, officials said Monday.

The Loma Fire started Monday on the southern edge of Santa Clara County and quickly spread to 500 acres, threatening radio and television antennas, said Cal Fire spokeswoman Stephanie Stuehler.

Meanwhile, a second blaze known as the Sawmill Fire erupted amid hot, dry conditions and gusty winds in Sonoma County north of San Francisco and forced the temporary evacuation of one of its 14 geothermal plants.

Brett Kerr, a spokesman for Calpine, which operates The Geysers geothermal complex, said evacuated employees were allowed to return to the plant, which started operating later Monday.

All employees were safe and accounted for and the flow of electricity from the facility was not disrupted, he said.

"Our remaining plants at the Geysers continue to operate normally and our team is constantly assessing the situation and will take all steps necessary to ensure the safety of employees and the preservation of our facilities," Kerr said in an email.

Cal Fire said the blaze near the small city of Cloverdale has charred about 1,500 acres, or more than 2 square miles of timber and dry brush.

Cal Fire spokesman Daniel Berlant said Monday that the fire also burned on plant property, but he did not know how close to the infrastructure.

The Geysers are located in the Mayacamas Mountains and are naturally occurring steam field reservoirs below the earth's surface. They are harnessed by Calpine to make renewable energy for homes and businesses across Northern California, according to the company web site.

The site says The Geysers, spreading 45 square miles along the Sonoma and Lake County border, is the largest complex of geothermal power plants in the world. Calpine owns and operates the 14 power plants at The Geysers, providing power for the equivalent of 725,000 homes, according to the site.

The Geysers supplies electricity to California's Sonoma, Lake and Mendocino counties, plus a portion of the power needs for Marin and Napa counties.

About 90 residents from 36 homes near the fire were under evacuation orders or advisories Monday.

The cause of the fire was under investigation as firefighters battling the blaze Monday in steep terrain braced for another day of temperatures in the high 90s with strong winds. The fire is 55 percent contained, according to Cal Fire.

Beth Willon contributed to this report