ANGWIN (CBS SF) — Racing against the clock in Wine Country, exhausted fire crews on Wednesday tried to take advantage of a critical window in the fight to contain the Glass Fire burning in Napa and Sonoma counties as yet another red flag warning loomed for the region.

Meanwhile, additional evacuations were ordered Wednesday evening for areas on the northern edge of the fire adjacent to Robert Louis Stevenson Park, between Old Lawley Toll Road and Pope Valley Road from Ink Grade Rd to Aetna Springs Road, as well as all recreational areas and mountain ridge trails in or near the park.

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An evacuation warning was issued for all areas north of Aetna Springs Road, extending west to the RLS Trail Head on Highway 29 to the Lake County line, between Highway 29 and West of Butts Canyon Road. Other addresses on Highway 29 from Tubbs Lane to the Lake County line and Old Lawley Toll Road remained on a warning.

The evacuation warning also applied to areas west of Highway 29 from the Calistoga City limits to the Lake County line, and north of Highway 128 from the Calistoga City limits to the Sonoma County line.

FIRE EVACUATION MAPS: Sonoma County | Napa County

As of Wednesday evening, the combined fires had grown to 51,266 acres and was 2 percent contained. The fire has destroyed at least 204 structures, Cal Fire said, including 36 single family residences in Sonoma County and 107 single family residences in Napa County.

Meanwhile, 26,290 structures are threatened.

Over 2,000 firefighters are working on the frontlines of the Glass Fire to increase containment.

“There were successful firing operations completed in Annadel Park yesterday, and from Bald Mountain on the county line in the Sugarloaf State Park down to Highway 12 along Adobe Canyon Road, as well as on the northern portion of the Sonoma County side of the line — from the end of Gates Road to the end of Sharp Road — to secure those two flanks of the fire here in the county. That mop-up is continuing,” said Cal Fire Division Chief Ben Nichols.

Cal Fire Operations Chief Mark Brunton said at an earlier briefing Wednesday that Calistoga continued to be threatened by the blaze and that the firefight in that area was challenging due to rough terrain “that makes it hard to get lines down.”

As if the terrain, flames and exhaustion were not enough of a challenge, the firefighters were also bracing for another dramatic change in the weather. The National Weather Service has issued a Red Flag Fire warning for the burn area from 6 p.m. Wednesday until Friday, predicting increasing winds and temperatures soaring 15-25 degrees above normal beginning Thursday morning.

“Periods of moderate northerly winds will develop as early as Wednesday night and last through Friday,” the weather service said. “This will combine with very low afternoon humidity and little or no nighttime recovery along with critically dry fuels.”

Raw Video: Glass Fire Burns in The Palisades (Napa County) adjacent to the Robert Louis Stevenson State Park (Video from Cal Fire LNU).

While the forecast fire conditions are not as dangerous as what firefighters experienced late Sunday night into Monday morning when strong winds whipped the Glass Fire into a period of explosive growth, the conditions will still be challenging.

“While not expecting the same critical fire conditions as what was observed earlier this week, critically dry and breezy conditions are expected in the area,” the weather service said.

Santa Rosa Fire Chief Tony Gossner urged residents to be mindful of their surroundings as increased winds arrive with the red flag warning, and to immediately report new fires that may pop up.

“This wind event is going to be serious enough for everyone to pay attention,” he said. “So whether you live in a warning zone or an evacuation zone, you need to pay attention to the weather and everything around you. It’s vital.”

Cal Fire also confirmed that PG&E has de-energized the transmission main from Middletown that was serving Calistoga for the safety of firefighters. PG&E is onsite energizing the generators at a back-up power generation site on lower Washington to serve the area.

PG&E crews were also moving through Angwin spraying fire retardant on power poles, hoping to slow the burn if the fire reaches town.

Evacuation Order Information:

Early Wednesday, the Glass Fire roared through the steep, rugged canyons near Angwin as an army of weary firefighters — on the brink of exhaustion from nearly two months of intense firefights in Northern California — battled to keep the blaze from spilling over Highway 29.

The small town has survived so far, but it is not out of the woods yet. The community remains under mandatory evacuation orders, leaving most streets deserted.

Mike Dunn has lived in Angwin all his life. He and several other residents have stayed behind. For the last couple days, there has been a lot of tension.

“Cal Fire has been working really hard. A few of us locals have stayed around, honestly, to help them,” Dunn said.

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During the battle to save the town, firefighters in bulldozers ripped a 50-foot-wide firebreak across the hillside that helped stop the fire from getting into Angwin while crews attacked the flames.

Dunn said he is being cautious and staying aware of where the fire is.

“We’re keeping an eye on things. But if the fire comes up behind us, we’re gone!” explained Dunn.

Another Angwin resident who gave his name as Cole said the few locals who remained are looking after each other.

“We got word that it jumped the fire line up on Summit Lake, and the homeowner here had some firefighting stuff set up to pump out of the pool with hoses and stuff,” said Cole.

Cal Fire officials also released details of a narrow Sunday night escape by a pair of firefighters as they were overrun by the flames. The incident took place at 11:45 p.m. as the blaze was raging in Napa County.

“The firefighters were on an active portion of the fire in Napa County where intense fire conditions, fueled by gusty off-shore winds, forced them to take refuge in fire shelters,” officials said.

After the wall of flames passed, the firefighters were able to flee. They were examined and determined to be uninjured, but several transport vehicles were heavily damaged.

Cal Fire officials split the firefight into two zones on Tuesday under the combined name of the Glass Fire. The east zone is the firefight in Napa Valley. The west zone is near Santa Rosa.

Fatigue is a growing factor among the more than 1,000 firefighters battling the flames.

“It’s been a long season,” said Cal Fire Operations Chief Billy See. “Most of them have been going since the middle of July without rest from fire to fire to fire here in the northern part of the state. So we are doing the best we can with the resources we have on the incident.”

A vast majority of the state and federal firefighters battling the Glass Fire were just ending a tough, month-long firefight with the nearby LNU Lightning Complex Fire that has burned 363,220 acres, destroyed hundreds of homes and claimed five lives.

The incident command team including See drove 100 miles north Tuesday from the Santa Cruz Mountains where they wrapping up management of the CZU Lightning Complex fire that burned 86,000 acres and destroyed hundreds of homes in the timber-rich region.

There was also a touch of irony for some of the fire crews. They have been here before. The current blaze was rolling through an area saved by the efforts of Cal Fire, local and federal firefighters from the devastating Tubbs, Nunn and Abode fires in October 2017.

“We are actually utilizing some of those control lines (left behind in 2017) on the outer edge to fight this fire,” See said. “This land has no fire history that’s recorded. This is burning in the acreage that we saved in 2017. So when it came over the ridge into Sonoma County, into Santa Rosa, this is all unburned vegetation that did not burn in 2017. It’s created a problem for the firefighters.”

As Wednesday dawned the most intense firefight was along Highway 29 near the evacuated Napa County communities of Angwin and Calistoga. Overnight backfires were lit along Highway 29 in an effort to rob the advancing flames of fuel.

“Fire exists in the hills above Silverado Trail north and east of town and the fire has approached 29 north of town but has not crossed,” Calistoga city officials posted late Tuesday. “While fire has come up to the Calistoga city limits, there has not been any fire within the city limits.”

While the fire continued to advance to the north, large and small vintners in the world-famous wine-growing region were still coming to grips with the devastation left by the blaze.

Along Silverado Trail, the damage ranged from an array of solar panels bordering the burned hillside at the Davis Estates Winery to total devastation of the famed Newton winery and Chateau Boswell.

Farther up the road, Fairwinds Estate Winery has also been devastated. The tasting room, bottling operation and fermentation tanks were all under the same roof and now the wines stored in barrels appear to be a total loss.

The fire also had its way with Hourglass Winery. Owner Jeff Smith said the fire circled around on the ridge above for about 24 hours before it finally dropped down early Monday morning onto the property. The 160-year-old residence that served as a welcome center for guests has been leveled. It also melted the plastic roof over the tanks, probably destroying the 2020 vintage that has been fermenting for a few weeks now.

But Smith says, because 2019’s wine was protected in an underground cave, the business will at least have some revenue this year.

“It’s a confluence of drought and climate change and a variety of different other factors…it’s very difficult,” Smith said. “I don’t think winemaking has ever been for the faint of heart, you know?”

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Don Ford contributed to this story.