SOUTH LAKE TAHOE, Calif. — The day feels toxic. All those tiny pieces of ash combining to shroud Lake Tahoe, a gray miasma that warns of the megafire just eight miles from the shore.
But the night. The night feels treacherous. Well after dark the Caldor fire engulfs pine trees with a crackling sound that crescendos into a roar. The flames don’t burn boughs laden with needles so much as they make them disappear with a blinding flash.
On Tuesday and into the early hours of Wednesday fire trucks and their bleary-eyed crews careened around hairpin turns, their headlights slicing through the murky gray smoke like the beam of a lighthouse on a foggy morning.
To traverse the front tendrils of the Caldor fire in the dead of night was to wonder what flames might shoot up onto the road, what bush might suddenly ignite, what carbonized towering evergreen might smash to the ground.
“Sometimes you hear trees falling every five minutes,” said Jason Allen, a firefighter who was hacking at a patch of ash-covered soil to reveal marble-size embers that a colleague extinguished with a hose.
Working by the light of his truck, Mr. Allen was in a wooded residential neighborhood a 10-minute drive from the shores of Lake Tahoe. This was the forward edge of the Caldor fire, although there were so many small spot fires that the landscape resembled more a series of large camp fires than a singular front.
On Monday embers had leapt down the steep slopes of the Tahoe basin, igniting the spot fires that now needed to be laboriously extinguished to prevent the fire from advancing toward the lake.
One of those embers had set alight a tree a few hundred feet from where Mr. Allen hacked the soil. Without warning the burning tree produced a shower of sparks, a bright Milky Way of fire.
“There’s a little bit of beauty in all this destruction,” Mr. Allen said.
The potential for destruction is clear. The fire is menacing tens of thousands of what fire statisticians dryly call structures — wooden vacation cabins, Thai restaurants, churches, cheap motels and five-star resorts. Since the fire landed in the Tahoe basin on Monday, everything has seemed vulnerable, all the places that crowd the lake.
On Tuesday night the fire ravaged stands of trees but did not seem to move in any consistent direction. A 40-minute drive from Lake Tahoe — in the hills across from the Kirkwood ski resort — one leg of the Caldor fire aggressively burned entire hillsides, casting a reddish glow into the night sky.
Closer to the lake the fire was more sedate in the early hours of Wednesday, burning more gently than it had the night before, when it forced its way into the basin.
The fire has a ways to travel before it reaches the lakeshore. A golf course, an airstrip, a timber merchant’s roadside lot crowded with neatly stacked logs and, perhaps more ominously, a propane storage facility — all separating the flames from the boundary line of South Lake Tahoe, the most populous city on the lake.
Given the erratic — and often terrifying — behavior of California’s megafires in recent years it seems anyone’s guess when and whether the fire will reach the lake.
Firefighters on Tuesday night were making a stand, calculating that they might be able to stop the flames at a creek along Highway 50, the road that wends down from the mountains toward South Lake Tahoe.
Minutes before midnight hand crews were clearing brush by the lights of their headlamps. A cacophony of chain saws, generators and pickaxes striking the soil competed with the rumbling of diesel engines of fire trucks lined up along the side of the road.
An engineer with a firefighting unit from Tuolumne County was drawing water from the creek and redirecting it through 2,000 feet of firehose to extinguish burning trees.
A few minutes away a crew from Clovis, a city in California’s central valley, went to investigate a brightly lit spot fire burning in the woods. The unit’s captain, Rob Wright, decided to leave it alone.
“There’s too many of these to put them all out,” he said.