Extreme weather hits much of the US this 'season of danger'

The United States is in the middle of the period commonly known as summer, or what some scientists now call the “danger season,” the period from May to October when extreme weather events peak and are likely to overlap due to the compounding influence of climate change.

So far this season, 99% of the nation's population has been affected by at least one severe weather alert, according to an assessment by the nonprofit Union of Concerned Scientists, which tracks National Weather Service heat, wildfire, storm and flood alerts on a map that's updated daily.

They found that only 79 counties in the United States (home to just 1% of the country's population) have not been affected so far this season. These counties are located primarily in Alaska, Michigan, Minnesota and Wisconsin.

The findings suggest a new reality is emerging for millions of Americans: A time of year once defined by lazy afternoons, swimming pools and backyard barbecues is increasingly marked by calamity.

“We are halfway there; we still have about another three months until the end of October,” said Juan Declet-Barreto, an environmental and social scientist who analyzed the latest map data. “The concern is that there is much more to go.”

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The data reveal other worrying findings, such as that almost a third of the country's population had already been under at least one extreme weather alert during the first week of the season. By mid-May, that figure had risen to almost half the population, 170 million people.

The past few months have been marked by scorching heat, choking smoke from wildfires and dangerous flooding.

In California, overgrown vegetation that turned to kindling amid record-breaking heat fueled the Park Fire after it broke out in July. The wildfire is now the state’s fourth-largest on record, at 429,263 acres.

The fire, one of nearly two dozen active wildfires in the state, is still only 40% contained.

A firefighter uses a drip torch to burn vegetation in front of the raging park fire in early August.

(Noah Berger/Associated Press)

Last month was also the The hottest month on record in the Golden State — and the second-warmest month on record globally. Two days, July 22 and 23, were the warmest days on Earth in modern climate records, according to the European Union’s Copernicus Climate Change Service.

But the dangers have extended far beyond California.

More than 60 million people were under severe weather warnings in the United States on Thursday, the map shows. This includes much of Puerto Rico, which was under a flood watch and warning due to Hurricane Ernesto.

Since the start of the season, extreme heat warnings have dominated much of the West Coast, as well as eastern Texas and parts of the Southeast. Fire warnings were most prevalent in the Pacific Northwest and the Four Corners region.

Meanwhile, flood warnings covered large swaths of the country, including parts of Texas inundated by Hurricane Beryl in July, and the East Coast, where Tropical Storm Debby left a path of destruction earlier this month.

Many of these alerts have occurred simultaneously, indicating heightened dangers for millions of people, said Declet-Barreto, the union's senior social scientist on climate vulnerability.

“What used to be associated with summer… has become a dangerous proposition for many people across the country,” he said. “There are fewer and fewer places where you can basically hide from these impacts.”

Alex Hall, a professor at UCLA’s Institute for Environment and Sustainability, said defining the months from May through October as “hazard season” makes sense because many risks — from hurricanes to wildfires to heat — are concentrated in the summer.

That doesn't mean there won't be impacts the rest of the year, though, especially in a state like California, which has been hit by atmospheric rivers and flooding in recent winters.

Still, he was not surprised that the map shows that 99% of the country has experienced an extreme weather alert since May.

“Global and continental indicators are really signaling that this is a year of climate change impacts,” Hall said. “When you combine the fact that we expect a significant fraction of the population to be affected by extreme weather in a place as large as the United States, and we’re in a year where climate change is really rearing its ugly head, I would say this is something to be expected, unfortunately.”

A tornado forms near Cedar Rapids, Iowa, in June.

(Nick Rohlman/Gazette via Associated Press)

The map also matches observations by the National Oceanic and Atmospheric Administration, which has reported 19 confirmed weather and climate disasters with individual losses exceeding $1 billion as of Aug. 8 this year. Together, they have killed at least 149 people.

Hall said such damage is likely to increase in the coming years, not only because of climate change, but also because of population growth and construction practices that may put more people at risk.

“We built our infrastructure for a different world, and in some ways we weren’t even very well adapted to the world we had,” he said. “And now we have a new climate.”

NOAA's latest seasonal outlook also indicates that more hazards are likely to be on the way in the coming months. Much of the country is expected to see above-average temperatures through October, while the entire East Coast is likely to see above-average precipitation.

“Stay vigilant and assume these impacts will continue through the end of the hazard season,” Declet-Barreto said, noting that it is still peak hurricane season in the Atlantic and peak wildfire season in the West.

A resident measures the depth of a flooded street in Pooler, Georgia, after Tropical Storm Debby passed through on August 7.

(Stephen B. Morton/Associated Press)

But those impacts may not be felt in the same way, he said. Many of the counties that have already had at least three weeks of extreme heat warnings are home to communities considered disadvantaged by the White House’s economic and climate justice assessment tool.

This includes densely populated areas suffering from the urban heat island effect, as well as rural and agricultural areas that are home to low-income populations and large numbers of agricultural workers working outdoors.

Still, the broader data is a stark reminder not only that people need to prepare for disasters at the individual and household level, but also that more government policies and interventions will be needed to ensure people can defend themselves.

For example, environmental groups are currently lobbying for the Federal Emergency Management Agency, or FEMA, to expand its definition of “major disaster” to include extreme heat and smoke from wildfires.

At the same time, the U.S. Department of Labor's Occupational Safety and Health Administration, or OSHA, is considering implementing heat standards to protect indoor and outdoor workers from rising temperatures, a move that would follow similar steps taken in California.

And while this summer's conditions may seem extreme, the season is currently on par with conditions in 2023, which was also marked by heat waves, flooding and other events in the United States, Declet-Barreto said.

The effect is expected to persist next summer, and certainly in the summers to come.

“These trends are likely to get worse because emissions trajectories have not slowed, they have not shifted to where they need to be for us to start defending against the worst of climate change,” he said, referring to rising atmospheric levels of carbon dioxide and fossil fuel emissions, which are a primary driver of climate change.

Even if humanity were to turn off the tap on greenhouse gas emissions today, emissions already in the atmosphere would continue to contribute to rising temperatures and climate instability, he said.

However, that doesn't mean people should stop taking steps to prevent the worst-case scenario.

“It’s about the choices we have as a society,” Declet-Barreto said. “This problem was created by choices people made long ago and now. And we have a solution that is also based on the choices we make now about emissions.”