Jeffrey Liu works in a hot warehouse on a hot dead-end street in one of the hottest neighborhoods in New York City. As he walked a half-mile to work on Monday morning, he knew it would be the hottest day of the year so far.

He reached Ibra Foods Importer & Distributor near Newtown Creek, in Maspeth, Queens, a few minutes before 10 a.m. He pulled down the brim of his baseball cap, which read “Thuglife Outlaw,” and drank the last drops from a little bottle of water. Then he shrugged and headed inside.

“There’s nothing I can do, man,” said Mr. Liu, 26, who lives in Fresh Meadows, Queens. “Look at me, I’m already sweating. And I’m just going to sweat all day.”

After a long spring that was unusually cool and notably wet, summer finally arrived in force. In Central Park the high reached 96 degrees, and the heat index, which combines temperature and humidity, hit 106, according to the National Weather Service.

At least the people in Central Park had some shade nearby.

The hottest places on hot days in New York City are the acres of asphalt at LaGuardia and John F. Kennedy Airports, according to a heat map published by the City Council. Smaller hot spots abound, usually where there are few trees, including a section of Jamaica, Queens, and around the giant food warehouses in the Hunts Point section of the Bronx.