Increasing fire weather places emphasis on defensible space

Fire requires three things to thrive: fuel, oxygen, and a spark. And right now, there is plenty of fuel drying out across the region.
A photograph taken from a peak located on the east side of Pyramid Lake in northern Nevada

Photo credit Ken Lund / Creative Commons BY-SA 2.0

Across the Great Basin, the above-average winter and spring precipitation has dramatically increased the amount of grasses, notably invasive cheatgrass. These fuels have already begun to dry out, raising concern for residents and fire officials. 

“This is going to be an extremely dangerous year because cheatgrass easily becomes flammable in the wrong conditions,” said Jim Shreck, a resident of remote northern Nevada.

Shreck has been living in the Pah Rah Range, north of Reno for forty years and has confronted wildfires nearly every season. He spends a few hours each day reducing the fuels around his home and property throughout the fire season. 

“It’s a constant chore to keep up on this stuff,” explained Shreck. 

He prefers mechanical clearing and labor over chemicals. Living near Cottonwood creek, he has surface water rights that has allowed him to develop about three acres of grass immediately surrounding his home. This “green space” eliminates any fuels near his home providing defense should a fire come though his property.

When Shreck is reducing his fuel loads, he is addressing an apex of another fire triangle, one used by wildland firefighters to gauge and manage a fire: fuels, topography, and weather. Topography and weather are both static, meaning we have no real control over them during a fire. The amount of fuel on the ground however, is something we do have control over.

The wildland fire behavior triangle. Courtesy National Park Service.

Due to more than a century of fire suppression across the West, many forests have built up a massive load of small in-filling trees, dead trees, and shrubs. These thick forests allow fires to climb from the ground and into the crowns, leading to wilder fire activity and more intense fires that spread much faster. To make matters worse, the fire season has been steadily growing over the past 50 years due to climate change.

Together, these two things have created a complicated fire outlook for much of the western United States.

‘A threat multiplier’

A study released by Climate Central, an independent group of scientists and communicators who research the changing climate, reported that fire weather days are on the rise. These are the hot, dry, and windy days that feed fires, often resulting in explosive and erratic activity of a wildfire.

“The kind of weather conditions that really encourage severe fire behavior, we’re seeing those more often throughout the year,” said Kaitlyn Trudeau, a data analyst for Climate Central. “It’s basically a threat multiplier,” said Trudeau “It means that the threat, the risk, is actually increased because of the weather conditions and fire behavior.”

Using weather data from over the past 50 years and from stations sprinkled across North America, Climate Central zeroed in on a few data sets. First, they looked at days with low temperatures from 45-50 degrees Fahrenheit (45 in winter, 55 in summer, 50 in spring and fall). Next was relative humidity levels that fall below regional thresholds of 20-40%. Finally, wind speeds of at least 50 mph sealed the triad.

“We wanted to have thresholds that not only would highlight days that were super super dangerous, but also days where Western utilities for example, might turn off your power,” explained Trudeau. Many power companies of the West, including NV Energy and PG&E, are monitoring these same variables and shut off power when conditions exceed thresholds.

Climate Central analyzed this half-century of data and found a noticeable rise in fire weather days across the country. For northern Nevada, there has been an increase of 31 fire weather days during the fire season. This does not necessarily mean a lengthening in fire season, though research has shown the season is growing, it means that there will be more hot, dry, and windy days that could result in fires burning hotter, faster, and in more unpredictable ways.

A graph showing a rapid increase in the number of days that are at or above fire weather thresholds, from 1973 to 2022.

“It’s increasing our risk of more extreme fires, but it’s also reducing our ability to address the issue of things like overcrowded forests,” said Trudeu, “because it reduces the number of days where you can safely do prescribed burning.”

Prescribed burning has always been a tool for fuels management, and now it appears these controlled burns have been gaining more traction as a realistic tool to address the massive fuel loads built up from over a century of a blanket fire suppression policy.

Building defensible space

Fuels reduction programs are a major part of the U.S. Forest Service’s program. There is specific funding for treatment in both the Bipartisan Infrastructure Law of 2021 and the Inflation Reduction Act of 2022.

But the public must also take action to reduce fuels, particularly in the wildland-urban interface. This is one of the fastest growing housing type across the West and exists in the liminal places between the forest and the city. Since 1990, the number of Nevadans living in the wildland-urban interface has jumped from just under 20,000 to around 570,000.

“We have more people moving into areas where we have increased risk of severe fire behavior. Creating defensible space is the best thing a community can do to prevent a wildfire from burning down communities,” said Trudeau.

“We’re very active [in] encouraging people to create defensible space, harden their homes, particularly if they live out in areas that are more prone to wildfires,” said Adam Mayberry, the public information officer for the Truckee Meadows Fire Protection District. The agency oversees over 6,000 square miles of unincorporated Washoe County and addresses most fires that spark in the wildland-urban interface.

“Defensible space is really a buffer around your property that’s free and clear of dry dead vegetation,” Mayberry said.

Above Palomino Valley, rancher Jim Shreck has a unique approach to maintaining defensible space on his property: cows. He has a handful of cattle that graze on his grass throughout the season. While he thinks cows are an obnoxious animal, Shreck said he sees the value in the service they provide. Additionally, he adamantly clears space around buildings on his property.

“Approximately 12-18 feet depending on how close the mountain is to the building, but usually somewhere around 10-15 feet and then we try to get rid of the sagebrush on the hill behind defensible space.”

Shreck has noticed more people and homes sprouting up around his property. While his neighborhood is more rural than a wildland-urban interface, he worries about the new growth. “Some neighbors don’t prefer to do anything [while] other neighbors go through the same process,” he explained.

Adam Mayberry with Truckee Meadows Fire said it’s ultimately up to all of us to do our part, especially given this year’s wet winter and explosion of dry, cheatgrass.

“It really comes down to the choices that people make, because 85-90% of all the fires that we respond to are started by humans.”


This site uses cookies to provide you with a great user experience. By continuing to use this website, you consent to the use of cookies in accordance with our privacy policy.

Scroll to Top