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As fire weather looms, a new report quantifies the rising number of 'fire weather days'

A map showing the change in the number of annual fire weather days since 1973 across the United States
Climate Central
Climate Central
So-called fire weather days, when temperatures and winds are high and humidity is low, have risen across the United States since 1973, especially in the American West.

A new report shows that the number of days out of the year with weather conditions that promote the spread of wildfires has jumped considerably over the last 50 years, a trend that’s most pronounced in the West.

The Climate Central report was based on data from nearly 500 weather stations from 1973 through 2022. The group was looking for trends in so-called "fire weather days," when temperatures and winds are high and humidity is low.

“While (in) most places it might be a couple of weeks more, maybe a month more, we're seeing some places that have two more months of fire weather days on average each year,” said Kaitlyn Trudeau, who conducted the report’s data analysis.

A map featured in the report shows especially dramatic rises in fire weather across the Southwest. A broad swath of New Mexico has seen an increase of 59 days over the last 50 years.

You can see the change in fire weather days where you live here.

The report largely attributes the shift to human-caused climate change, and recommends a rapid move away from fossil fuels, as well as adaptation to the troubling new reality.

Beyond increasing the risk of severe wildfires, the report notes that more hot, dry and windy weather can lead to utility companies shutting off power to avoid igniting blazes. It can also make it much more difficult to carry out prescribed burns, an important ecological and wildfire mitigation tool.

“As the climate continues to warm, we're not going to have safe enough conditions to…actually do things like prescribed burns as often as we need to, which is definitely alarming,” Trudeau said.

Alongside the trend in fire weather, the number of homes in the so-called wildland urban interface – where the built environment comes into close proximity to undeveloped landscapes susceptible to fire – has grown steadily. Several Western states – Nevada, Arizona and Utah – saw the sharpest percentage increase in such homes between 1990 and 2020, according to data included in the report.

That and other data, as well as the full report, can be downloaded here.

This story was produced by the Mountain West News Bureau, a collaboration between Wyoming Public Media, Nevada Public Radio, Boise State Public Radio in Idaho, KUNR in Nevada, the O'Connor Center for the Rocky Mountain West in Montana, KUNC in Colorado, KUNM in New Mexico, with support from affiliate stations across the region. Funding for the Mountain West News Bureau is provided in part by the Corporation for Public Broadcasting.

As Boise State Public Radio's Mountain West News Bureau reporter, I try to leverage my past experience as a wildland firefighter to provide listeners with informed coverage of a number of key issues in wildland fire. I’m especially interested in efforts to improve the famously challenging and dangerous working conditions on the fireline.

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