Unprecedented conditions make controlling California fires difficult

Reporting from Napa, Calif. —  To understand the challenges firefighters are facing on Day 6 of the massive wine country wildfires, it’s important to look at what happened over the last year.

A year ago, Northern California was about to begin what would become the wettest winter on record. The pounding rain and deep snow vanquished the crushing drought — but it also allowed brush and other vegetation to grow tall.

Related: Why this fire season is so bad

Then, the region saw an incredibly hot summer — with the temperature in San Francisco hitting an all-time record at one point.

That combination left huge amounts of dry brush ready to burn.

And with winds and dry conditions on tap for Saturday, it makes for another dangerous day with new evacuations and heightened anxieties.

Experts use a scientific formula to determine the potential of a fire, called its Energy Release Component, said Cal Fire spokesman Mike Smith..

On Saturday that potential is the worst “in recorded history,” Smith said.

Crews have not seen this amount of fuel this dry in the path of a fire in at least 26 years, he said.

“Today is going to be a much different day than you’ve experienced unless you were here” from the beginning, Tom Wright of the National Weather Service told crews at a Saturday morning briefing. “It’s a really critical day.”

Firefighters throughout the region are facing 10- to 20-mph winds, with gusts up to 40 to 45 mph, said Cal Fire spokeswoman Jaime Williams.

The winds and low humidity “will challenge the firefighting efforts,” she said. “When you have these winds, it helps contribute to the spread and the intensity of the fire”

The firestorms have destroyed an estimated 5,700 structures and caused at least 35 deaths and upward of 100,000 evacuations.

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