California is

poised to hit a fearsome milestone: four million acres (1.6 million hectares)

burned this year by wildfires that have killed 30 people and incinerated

hundreds of homes in what is already the worst fire season on record.

Flames have scorched an area larger than Connecticut

and fire crews at a blaze in the wine country north of San Francisco were on

high alert as forecasters warned of red flag conditions of extreme fire danger

into Saturday morning.

Winds up to 30 mph (48 kph) were forecast to push

through the hills of Napa and Sonoma counties as the Glass Fire, which exploded

in size earlier in the week, continued to threaten more than 28,000 homes and

other buildings.

Winds were blowing

at higher elevations on the western side of the fire and crews expected a long

battle to keep flames from jumping containment lines and prevent spot fires

from leaping ahead to spark new blazes.

The Glass Fire is the fourth major blaze in the

region in three years and comes ahead of the third anniversary of an Oct. 8,

2017, wildfire that killed 22 people.

Around the state, 17,000 firefighters were battling

nearly two dozen major blazes. Virtually all the damage has been done since

mid-August, when five of the six largest fires in state history erupted.

Lightning strikes caused some of the most devastating blazes.

Cal Fire Deputy Chief Jonathan Cox said wildfires

have scorched 3.9 million acres in California since Aug. 15.

“It’s likely that

over the next day or two we will crest the 4-million-acre mark. The biggest

year before this year was 1.54 million,” Cal Fire Chief Thom Porter said.