A dangerous, long-duration heat wave is gripping much of the eastern United States. Forecasters say extreme heat warnings have expanded from the Midwest into the Northeast, and the conditions are expected to persist through the end of the week and into the holiday weekend.
According to the forecast, heat indices are set to reach 100 to 110 across almost all of the East on Thursday, including the heavily populated I-95 corridor. The scope of the affected area means tens of millions of people are living under some form of heat advisory or warning.
The heat is expected to peak on Thursday and Friday. Meteorologists cited feel-like readings of about 110 in New York, 108 in Boston, 110 in Philadelphia and 113 in Washington, underscoring how intense the conditions could become in major cities along the coast.
Officials have flagged what they describe as a rare extreme heat risk. That designation is used when a long-duration heat wave offers little or no relief at night, which prevents the body from recovering and makes prolonged exposure especially hazardous for vulnerable people.
In New York City, forecasters said the heat index climbed into the low 100s and that air quality had turned unhealthy. Authorities have long warned about the dangers of extreme heat in the city, where officials say hundreds of people can die each year from high temperatures.
To help residents cope, New York City has opened hundreds of cooling centers across the five boroughs. Attention has also focused on outdoor and utility workers, who can find it unavoidable to remain exposed to the heat while carrying out essential tasks.
Forecasters said a brief break could arrive as the heat becomes slightly less extreme, but thunderstorm risks are expected to develop around the Fourth of July as storms ride the edge of the heat dome. Significant relief, they added, is not anticipated until the following week.