Major heat wave to expand from Midwest to East Coast, and it could last all week

The summer is coming in hot: As Thursday's solstice approaches, a heat wave is hitting the East Coast and Midwest and expected to last through at least Friday.

Almost 66 million people across the U.S. were under some level of heat alert as of Monday afternoon. Some 150 million people will experience temperatures above 90 degrees Fahrenheit on Monday, and readings could rise over 100 degrees for around 9 million people.

Heat warnings, watches or advisories were in place from Iowa to Maine, impacting cities including Detroit, Cleveland, Cincinnati, Pittsburgh, Philadelphia, Boston and New York City.

“The duration of this heat wave is notable and potentially the longest experienced in decades for some locations,” the Weather Prediction Center said on Sunday.

A boy cools off at a fountain during in Chicago. (Nam Y. Huh / AP)
A boy cools off at a fountain during in Chicago. (Nam Y. Huh / AP)

A strong heat dome is causing the extreme conditions. Temperatures could get as high as 25 degrees above normal in many areas.

New records could be set in some 200 cities from the Ohio Valley and the lower Great Lakes into the northern mid-Atlantic and the Northeast, according to the National Weather Service.

The NWS' Phoenix branch said temperatures reached 112 degrees there on Sunday — 7 degrees above average and just under the record of 115.

The Nevada Division of Emergency Management warned residents not to rely on fans to stay cool and to instead seek air-conditioned spaces such as libraries, shopping malls or the cooling centers that have been opened across the Southwest in recent weeks.

In New York, Gov. Kathy Hochul activated 50 members of the National Guard to help boost the state's response.

“As New Yorkers contend with more hot days due to climate change, it’s crucial that government and communities work together to protect those most vulnerable to heat, like older adults, outdoor workers, unhoused people, and those with preexisting health conditions,” Elijah Hutchinson, the executive director of the Mayor’s Office of Climate and Environmental Justice, said in a statement.

New York City’s more than 500 cooling centers are set to open on Tuesday.

Public school systems in at least two states have adjusted their hours in response to the heat wave. Schools in Worcester, Massachusetts, will end the school year a few days early due to the high temperatures. And schools in Buffalo and Rochester, New York, implemented half days for the rest of week to allow pre-K through 8th graders to leave after lunch.

Some parts of the U.S. are also expected to see heavy rain this week. In the Dakotas and Minnesota, the NWS said there is a chance of flash flooding and severe thunderstorms. Rain is pushing in from the Gulf of Mexico, as well, and expected to hit parts of Texas and Louisiana, possibly through Wednesday.

Research predicts more frequent and extreme weather events as climate change’s effects continue to intensify. Each of the last 12 months set a record for high temperatures, according to the European Union’s Copernicus Climate Change Service.

Deaths from extreme heat have increased in recent years. About 2,300 people in the U.S. died from extreme heat in 2023.