A heat wave is bearing down on large parts of America, forcing emergency workers to prepare for what could be record-breaking numbers of people in heat distress.

An excessive heat watch was in effect for southern New England, where forecasters warned of dangerous heat and humidity starting on Tuesday and lasting through Friday. It’s the first severe heat wave of the year for that part of the country.

When temperatures rise, it’s easy to overheat and, when that happens, important to cool off fast. Elevated body temperatures can cause brain damage, organ failure and, in severe cases, death.

“In heat exhaustion, the goal is to cool as quickly as you can,” said Dr. Aisha Terry, an associate professor of emergency medicine and health policy at George Washington University Hospital in Washington and president of the American College of Emergency Physicians. “There are definitely some health conditions where we have to be mindful of how quickly we correct the abnormality. This is not one of them.”

In all, millions of people across the United States are under extreme heat advisories. And if you think the country is getting hotter, it’s not your imagination. Between May 2023 and May 2024, the average American experienced 39 days of abnormally high temperatures as a result of climate change, scientists reported last month. That’s 19 more days than in a hypothetical world without human-caused warming.

Here’s how emergency medical workers are adapting to the risks.

Emergency medical workers and local officials across the country are spreading the word about cooling centers and swimming pools and stocking up on bottles of water to hand out to help offer relief from soaring temperatures and muggy weather.