What California’s wet winter and cool spring mean for wildfire season

An unusually cool spring has kept the copious quantities of snowpack that built up over the course of California’s stormy winter intact, generating cautious optimism among wildfire experts about what lies ahead this season.

But they are also warning that such conditions can change in an instant — and that new growth nourished by a wet winter could quickly become fuel for fire. 

“I’m personally feeling more optimistic about a manageable fire season for the rest of 2023,” Chris Field, professor and director of Stanford University’s Woods Institute for the Environment, told The Hill.

“But one of the things that’s quite dramatic about the drying of fine fuels is that just in a few days of hot weather, it can take you from fire risk to really terrifyingly high fire risk,” Field said.

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One of the most critical considerations in determining risk on a year-to-year basis is the length of time in which environmental “conditions are really ripe for fires,” according to Field. That window, he explained, is controlled by how quickly snowpack melts and dries out.

While the availability of moisture can shorten the fire season’s duration and decrease related risk, such conditions also bolster the growth of vegetation — which helps a fire spread once it starts, according to Field.  

“You have those two competing factors, and it’s always a little hard to know which ones are going to win,” Field said.

The professor noted that thin grasses can dry out in a matter of days. “It’s important to remember that for the finest fine fuels, they can really go from relatively moist to very dry and very flammable with just a few days of hot weather,” he said.

A period of hot, dry winds blowing from the continent out toward the coast can also exacerbate fire risks in an environment, like much of California, that is already vulnerable to extreme heat and drying events, Field added.

Nonetheless, Field stressed that the spring’s persistent cool weather has both helped maintain snowpack and moist soils in areas that lack snow — conditions that could make for a shorter fire season.

Robert Foxworthy, a spokesperson for the California Department of Forestry and Fire Protection (Cal Fire), likewise shared some optimism about the season ahead, while also encouraging residents to remain vigilant amid unpredictable conditions.

The status quo could change “if starting next week, we go into multiple 100-degree days and red flag warnings, which could, in turn, make it another one of those busy fire seasons,” Foxworthy told The Hill.

“But so far, the way things are setting up is we have received an incredible amount of moisture over the winter,” he continued. “We still have areas in the Sierra that are under multiple feet of snow.”

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During a recent visit he made to the mountains, Foxworthy said many spots were off limits, as they were “still under large amounts of snow.” Last year, these same areas had virtually no snow left and all the conditions necessary to become “one of those busier than normal fire seasons,” he continued. Ultimately, however, the 2022 season ended up “historically quiet in comparison to the previous years” — or what Foxworthy considers a testament to the unpredictability of wildfires.

Nonetheless, this year’s conditions have raised the chances of “lower than normal fire activity, especially in those higher elevation areas that are still under that snow,” Foxworthy said. He also seconded Field’s assertion that most wildfires would affect lower elevations, where grass is the main fuel.

That grass, Foxworthy explained, is beginning to dry out and will be receptive to fire much more quickly than the heavier fuels located further up the mountains.

Asked whether grass and forest fires tend to have the same potentially devastating effects, Foxworthy said it’s impossible to describe one as “more catastrophic than another.”

While grass fires contain lighter fuels and are easier to extinguish with water, they can also burn much faster and are more easily influenced by winds, he explained.

Sharing a similar perspective, Field noted that in heavily populated areas, there is “always a risk of a catastrophic outcome.”

Both Field and Foxworthy emphasized the importance of continuing to employ fuel management practices like prescribed burns, or the controlled application of fire to maintain forest health and remove overgrowth, which typically occur during the spring.

“The fact that we may be headed for a breather in 2023 is a great break and we should be grateful for that,” Field said. “But we can’t take our eye off the big picture, which is — we really need to be continuing to work to reduce the fire risk across the whole region.”

The window in which crews can work to reduce that risk through prescribed burns is narrow, as such preventative action must occur when conditions are dry enough to kindle a flame but before wildfire season starts, Field explained.

“You are at the mercy of nature in terms of when you can successfully do burns,” he said.

Since the same crews often conduct both fire suppression and prescribed burns, those involved in the latter sometimes need to be pulled away to the former when they occur at the same time, Field noted.

Foxworthy said that despite this year’s wetness, conditions for carrying out such burns have actually been more favorable than in previous years, when spring transitioned right into fire season.

“It being quieter and cooler and the fact that we’re having more favorable conditions is actually leaving us being able to conduct more of those burns,” he added.

Regardless of the current quiet, Foxworthy urged residents to take advantages of the lull by preparing their properties for wildfire activity now, rather than adopting a “false sense of security.”

“This is California, and we will have somewhere in the state that does have fires and does get that fire activity,” Foxworthy said.