Northern California wildfires are burning much earlier this summer. Here's why.

You aren't imagining it: California's wildfire season really has started earlier than usual this year.

The state's biggest fires usually don't strike until August or later. This year, California already is besieged with two major fires, and it's the first week of July.

The County and Pawnee fires have burned through a combined 85,000 acres northwest of Sacramento and aren't done yet.

The County Fire, which roared to life in rural Yolo County on Saturday afternoon, was spreading at nearly 1,000 acres per hour. It quickly spilled into Napa and Lake counties and was only 5 percent contained early Tuesday.

The 10-day-old Pawnee Fire was a more reassuring 80 percent contained on Monday, but it already had jumped its containment line once, and mandatory evacuations remained in effect for the Double Eagle subdivision of Lake County.

The two fires are merely a taste of what's to come, the earliest markers of what's shaping up as a particularly nasty year, fire officials and climatologists said Monday.

"It has been basically very dry since the beginning of April," said Paul Ullrich, a climatologist at UC Davis. "I wouldn't be surprised if the (fire) season is among the worst on record."

Already this year, Cal Fire has responded to 2,626 fires. That's about 260 more than at the same time a year ago, said agency spokesman Scott McLean.

McLean said it has gotten to the point that one fire season is bleeding into the next. "We're responding to wildland fires year round now," he said.

He added that the season is just getting geared up. "Southern California hasn't even lit off yet," he said. "And usually they start first, and the north follows up."

That could change in a matter of days: The National Weather Service on Monday warned of "potentially critical fire weather" in the Los Angeles area later this week, as temperatures hit triple digits.

Why has the fire season shifted dates on the calendar? The reason partially has to do with climate change, said UCLA climatologist Daniel Swain. Simply put, California is getting hotter.

"The overriding signal is that when it's warmer, whatever vegetation that's there ... it has the potential to burn more," Swain said.

The situation has turned dire the past two years. A cruel combination of weather extremes — the record rainfalls of 2017 followed by two summers of scorching heat — left a rich carpet of highly combustible grass and other vegetation.

The results have been almost predictable. Last year saw the deadliest and costliest wildfires in California history: the wine country fires, which killed 44 people in October.

This year, the tables are set for another difficult season.

Not only is there plenty of unburned vegetation left from last year's rain — known as "carryover fuel" in firefighting circles — climate change appears to be drying out the grasses and forests sooner than before.

Temperatures in much of California in June were as much as 2 to 3 degrees higher than usual, said Tim Brown of the Western Regional Climate Center in Reno. Last summer, California set a record for heat; temperatures were 3 degrees above the historical average.

A hot June also meant a dry June. Although the month usually gets almost no rain, this year it was bone dry with very low humidity. That made a difference, Brown said.

"A cool, wet June ... would have delayed fires," he said.

There's also some bad luck involved. Strong winds caused the Pawnee Fire in Lake County, which had appeared to be abating, to jump its containment lines and start spreading again Saturday. The fire had consumed 14,900 acres by Tuesday morning.

The County Fire in Yolo County, fueled by high winds, was spreading at an extraordinary rate, nearly 1,000 acres an hour. The fire, which raced into Napa and Lake counties, had chewed through 70,000 acres as of early Tuesday.

"Those winds become the dominating factor," Swain said.

Officially, wildfires have burned 53,000 acres this year in California, although McLean said those statistics don't include the 59,000 acres burned so far by the Pawnee and County fires. Last year at this time, the total acreage consumed by wildfires was just 39,000 acres.

The worsening of California's wildfires has turned into a political issue. PG&E, whose transmission lines and power poles have been blamed by Cal Fire for the bulk of last fall's deadly wine country fires, is pushing a bill, SB 901, that would ease utilities' financial liabilities for wildfires in the future. Late Monday, Gov. Jerry Brown announced the formation of a bipartisan legislative conference committee aimed at moving the bill forward and hashing out disagreements.

PG&E has warned investors that its liabilities from the wine country disaster could exceed $2.5 billion and hinted it might have to seek bankruptcy protection. It argues that with climate change, wildfires are the "new normal" and aren't the fault of electric utilities.

Critics say PG&E must be held financially accountable for the wine country fires, which caused an estimated $10 billion in damages.

The early start to the fire season already has caused some holiday fireworks cancellations. The city of Winters, in Yolo County, scrapped the fireworks scheduled for Tuesday.

The rest of the summer looks bleak. The federal government's National Interagency Fire Center, in its monthly forecast Sunday, said California can expect "elevated fire potential" for the balance of the summer.

It added, somewhat ominously: "August is the peak of the Western fire season."

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