Heat wave maps: How long the dangerous temperatures will last

Heat alerts are in effect on Thursday for more than 70 million Americans.

June 20, 2024, 4:05 PM

Heat alerts are in effect for 16 states from Maine to Kentucky as the dangerous heat wave continues.

Boston and Manchester, New Hampshire, both reached a record high of 98 degrees on Wednesday.

In Caribou, Maine, the heat index -- what the temperature feels like -- hit an all-time high of 103 degrees.

PHOTO: A vendor sells ices as people try to stay cool on June 19, 2024 in Newark, New Jersey.
A vendor sells ices as people try to stay cool on June 19, 2024 in Newark, New Jersey.
Spencer Platt/Getty Images
PHOTO: Mathew Calderon, 4, walks through a fountain at Georgetown Waterfront Park amid a heat wave in Washington, U.S., June 19, 2024.
Mathew Calderon, 4, walks through a fountain at Georgetown Waterfront Park amid a heat wave in Washington, U.S., June 19, 2024.
Craig Hudson/Reuters

The heat won't relent on Thursday.

Temperatures are forecast to hit a scorching 99 degrees in Concord, New Hampshire; 97 degrees in Hartford, Connecticut; 95 in Boston and Pittsburgh; 93 in Philadelphia and Indianapolis; and 91 in New York City.

PHOTO: This weather map shows excessive heat today, June 20, 2024.
This weather map shows excessive heat today, June 20, 2024.
ABC News

In the Northeast, the heat might force Amtrak trains to slow down, causing up to one-hour delays, according to Amtrak.

In Washington, D.C., the heat is forcing Metro trains to slow to below 35 mph.

This weekend, the heat dome is heading south and west, with the heat index forecast to climb as high as 110 degrees in some places.

By Sunday, the temperature is forecast to skyrocket to 101 degrees in Oklahoma City and Washington, D.C., and 99 degrees in Nashville, Tennessee.

PHOTO: This weather map shows high temperatures into the weekend.
This weather map shows high temperatures into the weekend.
ABC News

There are hundreds of deaths each year in the U.S. due to excessive heat, according to CDC WONDER, an online database, and scientists caution that the actual number of heat-related deaths is likely higher.

Click here for tips on how to stay safe in the heat.

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