This story originally appeared on Grist and is part of the Climate Desk collaboration.

Last summer, a monstrous heat wave descended on the United States. It claimed four lives in Maryland, one in Arizona, and one in Arkansas. Temperatures skyrocketed, with heat indexes—the measure of how hot it feels outside—reaching between 100 and 122 degrees Fahrenheit in some parts of the country. Power outages wreaked havoc on the residents of New York City and Washington, DC, who were left sweating in their homes.

That heat wave caused fatalities on par with many of the named hurricanes that circulate in the Gulf of Mexico. But unlike hurricanes—the worst of which carry memorable household names like Harvey, Sandy, or Maria—the July 2019 heat wave went nameless.

Now, as triple-digit heat waves set records around the country and around the world, a group of health experts, climate scientists, and policymakers are trying to give them names and rankings, just like hurricanes. In doing so, they hope to remind the public that extreme temperatures aren’t just an excuse to go to the beach—they can also be fatal.

The World Health Organization estimates that from 1998 through 2017, more than 166,000 people died due to exposure to extreme heat. One catastrophic heat wave in 2003 killed tens of thousands in Italy and Spain. In the US, over 600 people succumb to extreme heat every year, outstripping the deaths from hurricanes, floods, or tornadoes in most years. And with climate change, sweltering temperatures are becoming all the more common.

“It’s this pervasive, pernicious, climate-induced threat that is little known,” said Kathy Baughman-McLeod, director of the Adrienne Arsht-Rockefeller Foundation Resilience Center at the Atlantic Council. “We call it the silent killer.”

Baughman-McLeod is one of the leaders of the Extreme Heat Resilience Alliance, a brand-new initiative formed by city governments, nongovernmental organizations, and scientists. By naming and providing severity rankings for predicted heat waves before they strike, the alliance hopes to spark public awareness and encourage local cities and states to take preventative measures—setting up air-conditioned cooling centers, for example, and sending search-and-rescue teams to check on elderly and vulnerable populations.

For those who live in the path of dangerous hurricanes, knowing the names and dangers of tropical storms is a must. “I spent 25 years in Florida,” Baughman-McLeod said. “And I know the difference between Category 1 and Category 3. That’s all very standard for people who live near hurricanes.”

But few people have a similar understanding of the dangers of extreme heat. High temperatures put extra stress on the body, forcing blood toward your core and making your heart beat faster. For older adults who have underlying conditions, that added stress can be fatal. In the wake of a catastrophic heat wave, many elderly individuals are found dead at home, sometimes with broken air conditioners. Young people and outdoor workers can also be killed by heat stroke when temperatures crest 100 degrees.

Bob Ward, the policy director of the Grantham Research Institute on Climate Change and the Environment at the London School of Economics, has been arguing for naming heat waves in the United Kingdom since last year. He thinks that it might push the UK government to upgrade buildings to be more resilient to heat and encourage individuals to check in on friends and family.

“People should be thinking about their elderly relatives and neighbors and looking out for them,” he said. “People tend to do that in cold weather, but they’re less likely to do that in hot weather. There’s this view that hot weather is somehow lovely for everyone.”