A Real Scorcher: Simple 'Hot Day' Metric Forecasts Increases in Utah Wildfire by 2050

As wildfire behavior shifts in Utah, land managers are asking urgent questions: How big will future fires be? How often will they burn? While wildfire remains a natural and beneficial force in many ecosystems, forests are increasingly struggling to adapt to changing conditions. Leaders and land managers are looking for clearer ways to anticipate what comes next — and how to prepare.

New research from Joseph Birch, Yoshimitsu Chikamoto and Jim Lutz from the Quinney College of Agriculture and Natural Resources uses a simple strategy to find the answer. The team compared "hot days," when the air temperature topped 80°F, to almost 1,500 wildfires between 1984 and 2021. They found that the simple metric was a reliable predictor for the occurrence of wildfire on a local scale.

And if the pattern holds, they report, the state will experience major increases in land burned and fire frequency by 2050 — up to 60% more in forest lands and 130% more for non-forested areas like shrublands and rangelands. This highlights the growing need for residents to understand the risks and to take responsibility for property protection, especially considering new fees announced for higher-risk areas under Utah law HB48, an effort to address availability and affordability of home insurance in the state.

In Utah’s dry climate, hot days are a primary driver for how quickly fuels like dead logs dry out, Birch said. Since 1960, the frequency of these days has increased by about one day every five years. The number of hot days is a metric easy for the public to track and serves as a reliable indicator of when wildfire risk is escalating in the state, according to the research.

Fire ecology is more complicated than daily weather, of course. Fire patterns are influenced by drought, forest health and snowpack. Fire behavior responds to wind, air temperature, relative humidity and atmospheric shifts. Though statistically strong, the standard approach to wildfire prediction that incorporates all of these factors isn’t always useful on a local level.

“The risk of future fire is very uneven across ecosystems and land types across Utah,” Birch said. “Some areas, like rangelands, have more murky patterns. We know that all ecosystems will see more and larger fires, but some ecosystems, like our forests, will see very dramatic and outsize changes from what we have today.”

The goal with this new approach is to make things easy to interpret and apply, according to the researcher team.

“By simplifying it to bare bones, we hope to make patterns easier to track, understand and act on,” Lutz said. “We hope to empower Utah leaders who have to make immediate and short-term management decisions with actionable information.”

The team focused on the near future — the year 2050 — to try and make the findings more relevant to homeowners and state planners. High-elevation forests statewide could see a 60% increase in area burned and a 24% increase in fire frequency in the next 25 years. For residents living in the wildland-urban interface, the risk is increasing as well. Land area burned in wildland-urban interface shrublands and woodlands is projected to increase by half over a quarter century.

"Such a simple and yet effective climate metric also enables the development of predictive capabilities for future wildfire threats on seasonal, interannual and potentially decadal timescales,” Chikamoto said.

The researchers emphasize that while the trend is significant, it could be mitigated on some levels by preparation:

• Defensible Space: Homeowners can trim vegetation and shrubs near their homes to reduce fuel sources that would connect to an uncontrolled fire.
• Infrastructure Investment: Local leaders can choose long-term investments in firefighting infrastructure, equipment and expanded professional training, such as programs already underway at USU.
• Fuels Management: Prescribed burns and mechanical thinning help prevent "mega-fires" by breaking up the fuel that allows fires to spread uncontrollably.
• Extended Season: The public can be aware of an increasingly long summer season of high fire danger, with red flag conditions stretching into October.

“By understanding these climatic thresholds today, we can begin to make gradual, consistent changes to help prepare for what’s ahead,” Chikamoto said. “Research like this offers a peek behind the curtain for the reality of tomorrow.”