Summer Is Hot, but This Is Abnormal

Scorching weather has far outstripped old expectations, but many Americans still have trouble seeing high temperatures as a distinct hazard.

A person with an umbrella walking past an electronic sign showing the temperature to be 122 degrees Fahrenheit
Ralph Freso / Getty

About the author: Kathy Baughman McLeod is the director of the Adrienne Arsht–Rockefeller Foundation Resilience Center at the Atlantic Council.

Summer is hot. This is among the most basic weather concepts that we learn as children and accept without question. Heat and even heat waves have always been a reliable hallmark of the season between the June solstice and the September equinox. And yet recent weather has far outstripped that norm. For most of last week, the daily high temperature in Phoenix reached or exceeded 115 degrees, breaking records even in that desert city. This weekend, a “heat dome” is expected to raise temperatures above 110 degrees in Washington, Oregon, and Idaho—places whose physical infrastructure is not well adapted to such heat.

Climate change is upending old rules and disrupting predictable weather patterns: Heat waves, wildfires, and tropical storms and hurricanes—the trifecta of extreme weather events—now arrive earlier than expected, occur with greater frequency and intensity, and stretch well past their historical timelines. But too few Americans think about heat waves, which claim more lives globally than any other weather-related hazard, as a problem for which systematic, long-term preparation is warranted. To protect human life as temperatures soar, we need to conceive of what we might call heat season as a phenomenon distinct from summer—a part of the year that people in much of the country have traditionally viewed with great fondness.

Historically, wildfire season in the United States has begun in May and ended in October; however, wildfires raged well into December last year. The 2020 season, which included 30 named storms, was the most active on record. The annual Atlantic hurricane season formally begins June 1 and ends November 30. The emergence of Tropical Storm Ana on May 22 made 2021 the seventh consecutive year that a storm strong enough to be named formed off-season. Because of this early storm activity, the National Weather Service has been considering moving the start of hurricane season to mid-May.

Heat waves, too, are arriving alarmingly early. Barely a week into summer, a heat dome affecting 40 million Americans lifted temperatures above 100 degrees not only in Phoenix but in places such as Denver, Salt Lake City, and Billings, Montana. Northern locations not typically plagued by extreme heat were hit even earlier. In early June, the city of Caribou in northern Maine experienced back-to-back highs of 92 degrees. Amid the heat wave, nearby towns sent students home, the Bangor Daily News reported, and at least one restaurant closed its kitchen to prevent heat sickness.

Early-season heat waves are likely to be more lethal than those later in a given summer. That’s partly because people are caught off guard and less acclimated to high temperatures and partly because, as a macabre 2012 The Washington Post article noted, heat preys on the vulnerable, “leaving behind fewer susceptible people for future heat events.” Promoting public awareness of and encouraging state and local governments to plan early for the problem—much as those in coastal communities do before every hurricane season—could save lives. This is why the organization that I direct, the Atlantic Council’s Adrienne Arsht-Rockefeller Foundation Resilience Center, is urging the National Oceanic and Atmospheric Administration and its National Weather Service to designate the months of April through October as U.S. heat season. Doing so every year would help sound the alarm for approaching emergencies, build a culture of preparedness, and improve communication with the public—much like the National Hurricane Center set out to do when it began to name tropical storms and hurricanes in the 1950s. Indeed, our organization, along with a panel of scientific experts, is also developing a process of categorizing and naming individual heat waves intense enough to do serious harm.

At the moment, the best annual reminder Americans get about the worsening risk from high temperatures is National Heat Awareness Day, observed every year on the last Friday of May. A stronger warning is urgently necessary. A heat wave doesn’t char millions of acres in a single event, rip roofs off houses, or cause massive flooding, but heat does wreak quiet havoc on the health and economic well-being of billions worldwide. The effects are far more subtle, albeit no less pernicious, than the visible devastation caused by its more dramatic cousins. Data on heat-related mortality are also scant because many such deaths are attributed to other medical conditions like seizures or heart attacks—which is why many experts have dubbed heat the “silent killer.

Meanwhile, the economic ramifications of heat waves become clearer every year. In 2017, 120-degree heat grounded flights in Phoenix. In Washington, D.C., and London, train service abruptly halted when tracks melted. And during the pandemic, some New Jersey COVID-19 testing sites had to shut down because of high temperatures. According to the International Labour Organization, heat stress is also projected to reduce total working hours worldwide by 2.2 percent by 2030—“a productivity loss equivalent to 80 million full-time jobs.”

The Miami physician Cheryl Holder, an expert on the links among climate change, health, and poverty, has argued that heat disproportionately imperils older Americans, outdoor and manual workers, and Black, brown, and Indigenous communities. One of her patients, she has noted, is an elderly woman with chronic conditions including asthma and chronic obstructive pulmonary disease. Heat waves mean higher energy bills and force this patient to choose between paying for her asthma inhalers and keeping the air conditioner running.

The direct physical threat may be most acute in cities, where temperatures on a scorching summer day can vary by as much as 45 degrees from a well-shaded area to one without trees. This is one more way in which poor Americans bear the brunt of broiling temperatures. As noted by the nonprofit American Forests, a map of tree cover in America’s cities is in many cases a map of income and race.

Communities can do much more to address these problems equitably. This spring, Daniella Levine Cava, the mayor of Florida’s Miami-Dade County, named the world’s first chief heat officer to focus on protecting the health and livelihoods of the county’s most vulnerable residents. My organization is defraying some of the costs of creating this role. We have also established the Extreme Heat Resilience Alliance and an offshoot, the City Champions for Heat Action Initiative, of which Miami-Dade is a founding member. The cities of Athens, Greece, and Freetown, Sierra Leone, have also signed on and will appoint their own chief heat officers. We invite U.S. cities to follow suit.

Despite some recent progress, Americans remain woefully unprepared for the growing threat of extremely hot temperatures and conditions. By loosely equating heat with summer, we have unwittingly hampered our ability to address the risks that a worsening climate poses to our social fabric, economies, and environments. Heat season is upon us. We must acknowledge our risks to manage and survive them, and that process begins by calling the silent killer by its real name.