Red flag warnings posted in 8 states as millions face increased risk of wildfires

The National Weather Service posted red flag warnings in eight states on Tuesday, meaning that tens of millions of Americans currently face heightened risk of wildfires due to the combination of high winds and unusually dry conditions.

Low humidity and winds over 25 mph, with gusts as high as 65 mph, are expected in Texas, Oklahoma, Kansas, Missouri, Colorado and portions of Arizona, New Mexico and Nebraska.

On Friday, similar conditions resulted in more than 130 fires across Oklahoma, the state’s Department of Emergency Management said, killing at least four people, injuring 200 more and destroying over 400 homes.

When are red flag warnings issued?

The National Weather Service issues red flag warnings to “alert fire managers on federal lands to conditions that are highly unfavorable for prescribed burns,” the agency says on its website.

That determination is based on three factors: “how much water is held by small vegetation such as grass, leaves, and mulch that take only about ten hours to respond to changes in dry/wet conditions,” relative humidity readings of less than 25% for several hours, and wind speeds of “at least 15 mph for several hours,” the NWS states.

Those conditions, which dramatically increase the risk of wildfires, typically occur in the fall and spring. But the deadly fires that ravaged much of the Los Angeles area in January show that they can occur at other times, as well.

The conditions experienced during red flag warnings do not guarantee that a wildfire will occur, but they make them much more likely. A study by the World Weather Attribution, a consortium of climate scientists, found that “from 2006 to 2020 8% of wildfires in the western U.S. and 19% of large wildfires” happened on days on which a red flag warning was issued.

Not just a western problem

As the past year has attested, red flag conditions are not just a problem for western states. On Monday, they were posted across most of South Florida; earlier this month, they went up in the Carolinas. In October, red flag warnings were issued in New York, Connecticut and New Jersey, where wildfires threatened hundreds of homes.

“In response to the dryness, combined with other local factors (warmth, low humidity, strong winds), the National Weather Services offices across the Northeast have issued an unusually high number of Red Flag Warnings for the month of November to date,” the NWS said in a message posted to its website on Nov. 21, 2024.

Ongoing drought conditions in New Jersey have led to a 266% increase so far this year in the number of wildfires there over last year, Gothamist reported this week.

“We did, in fact, have a drier winter season coming off an incredibly, incredibly dry late summer and fall,” Shawn LaTourette, Department of Environmental Protection commissioner, said during a media briefing last week.

The climate change link

Numerous studies have shown that rising global temperatures are increasing the length and intensity of wildfire season.

“Climate change, including increased heat, extended drought, and a thirsty atmosphere, has been a key driver in increasing the risk and extent of wildfires in the western United States during the last two decades,” NOAA states on its website.

We also know that evaporation rates have increased dramatically as temperatures continue to rise, making vegetation like grasses and leaves much more susceptible to burning.

The extent to which climate change is affecting wind speeds is still a matter of debate, but a 2019 study found that wind speeds have increased across Europe, North America and Asia since 2010.