Paramedics in Washington, D.C., burned through their supply of ice packs on Tuesday, and residents cranked up the air-conditioning as far north as Maine, as parts of the East Coast endured the hottest day in over a decade.

Central Park in New York City hit 99 degrees by 1:30 p.m., the warmest temperature recorded there since 2012. Other cities along the Atlantic Seaboard reached similar marks, with Logan International Airport in Boston hitting 100 — the hottest ever recorded for the date — and temperatures soaring into the triple digits from Florida to New Hampshire.

Scorching early-summer heat has become more common in recent years as climate change drives global temperatures past record levels. But that doesn’t make it any easier to cope with, especially in places that weren’t built for long, hot summers. Here’s how people in some of the sweltering cities dealt with the heat on Tuesday.

Washington, D.C.

It was only morning but the temperature was already close to 100 degrees, and Jared Snyderman, the emergency medical services supervisor on duty for one of the city’s firehouses, raced to respond to one of several heat-related calls that he would receive throughout the day.

This time the call involved a young woman and her toddler, out in a stroller. Mr. Snyderman and the other emergency workers who responded said they were down to their last few ice packs. They placed one on the toddler’s torso and gave a second to the young woman. “We’re not going to let the child die,” said Mr. Snyderman, 38.