California is entering its summer fire season with a high level of flammability. The hottest and most fire-prone months of the year are ahead. Conditions in the state are a striking example of escalating fire potential in the drought-stricken West.

How the season unfolds will depend on a number of factors, including where ignitions occur and the duration of summer heat waves.

But the outlook is poor at this time, given deepening drought, abundant dry fuels and hot early-season temperatures.

Crystal Kolden, a fire scientist at the University of California at Merced, said that what really stands out about this year’s fire season is how dry conditions are at higher elevations this early in the summer.

The Sierra Nevada region is in the midst of one of its driest water years on record and saw rapid loss of critical snowpack this spring. Statewide snowpack officially hit 0 percent May 27. This was followed by an intense early-season heat wave as June got started.

Lingering snowpack and moist soils would normally suppress both fire growth and ignitions in these mountainous areas in June and July.

“July is our peak month for lightning ignitions,” Kolden said. “There is a greater potential for lightning fire in the high country this year and a greater potential for it to spread.”

Last August, the SQF Complex fire began with a lightning strike and burned nearly 175,000 acres in and around Sequoia National Park. It may have destroyed at least 10 percent of the world’s giant sequoias, historically one of the most fire-resilient species.

A recently published study found that, since the mid-1980s, Western forest fires are moving into higher altitudes as temperatures rise, reaching elevations that previously would have been too wet to burn.

Dead and downed trees from a drought-stressed landscape have compounded the problem, making it more likely that fires will burn hotter and more severely, making them more difficult to contain.

“We still have a lot of accumulated dead material from the previous drought, and we are starting to accumulate more during the current drought,” Kolden said.

Wildfire season is a natural part of many ecosystems, but climate change has these fires burning hotter and longer throughout the year. (John Farrell/The Washington Post)

Expect bigger fires in the coming weeks

With conditions already parched, most of the state faces an increased chance of large and possibly destructive fires for several more months. That is true even in Southern California, which is in less severe drought than areas to the north.

“Right now, our fuels are very dry — drier than they would normally be and drier than last year at this time,” Tom Rolinski, a fire scientist with the utility Southern California Edison, said in an interview.

Even though the lack of rain has meant sparse grass growth this year, which may help to mitigate fire spread and roadside ignitions, bigger fires will be driven by how much moisture is in live plants and shrubs, he said. Moisture values are running far below normal and will continue to decline until the wet season arrives sometime late in the year.

For example, live fuel moisture readings are approaching 80 percent in Los Angeles County, a typical threshold for rapid fire growth. These numbers will only drop more in coming weeks.

“We’ll start to see fires carrying through larger vegetation and consuming that vegetation,” he said. “We’ll see a greater frequency of large fires in the coming weeks.”

Heightened fire potential across the West this summer

The National Interagency Fire Center’s outlook shows above-normal fire potential for much of the West, as well as the northern plains, given widespread drought in addition to the expected warmer and drier-than-normal conditions this summer.

Extreme heat is already overlapping with drought in Western and northern tier states. California, Oregon, Idaho, Utah, Wyoming and North Dakota all saw record-breaking high temperatures in early June, and all are now regions of expanding and intensifying drought.

Heat was a key ingredient in last year’s record-breaking fires in California and the Pacific Northwest, as well as those in Arizona and Colorado. And heat — or the lack of it — will help determine how the summer fire season plays out.

Despite the drought, some regions have seen lower-than-expected fire activity so far this season. This is especially true in the southwestern United States.

“Here we are approaching mid-June and what looked to be a horrific fire season has turned out to be quite slow this year,” said Richard Naden, a fire meteorologist with Predictive Services in Albuquerque.

He attributes the lack of fire activity mainly to sparse grass growth due to dismal monsoon rains over the past two seasons, and also to the absence of intense heat waves.

However, he cautions that there are three to four weeks left in the season before the annual monsoon sets in, and that timber areas remain susceptible to large fires. Two fires exceeding 50,000 acres are burning in southeastern Arizona at present.

“We still have high potential down here, even though things have been tempered by the lack of fine fuel growth and heat,” he said.

The Southwest monsoon, which streams moisture northward from the Gulf of California and into Arizona, New Mexico and the Four Corners region, is expected to arrive on time. It typically shuts down the southwest fire season by early to mid-July.

But that moisture will also bring the threat of lightning ignitions farther north, including to higher elevations in California.

“Overall, it’s shaping up to be a busy fire season and a very active fire season,” said Rolinski of Southern California Edison. “The fact that our fuels are drier than normal, and we are in exceptional drought, is very concerning to us.”