A heat wave heads to the South while the Midwest and East Coast confront storms

Updated June 23, 2024 at 17:18 PM ET

For over a week, a major heat wave has brought scorching temperatures to the Midwest and Mid-Atlantic. Now, severe storms and widespread floods threaten those regions, while the hot spell moves to the South.

As of Sunday, more that 123 million people in the U.S. were under heat alerts, including large swaths of South Dakota, Nebraska, Kansas, Oklahoma, Iowa, Missouri, Arkansas, Louisiana, Florida, Connecticut, Pennsylvania, New York, New Jersey, Delaware, Virginia, Maryland and North Carolina.

The Midwest began to see temperatures cool down this weekend, while the heat is expected to peak Sunday from Washington, D.C., to New York. In the South, the hottest weather — which is forecast to be well into the triple digits — is expected to appear early this week.

On top of the hot spell, widespread showers and thunderstorms are forming in the Northeast. The National Weather Service expects flash floods, damaging winds and tornadoes to threaten the New England region on Sunday.

AP / Sioux County Sheriff

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Sioux County Sheriff

The extreme temperatures are caused by a heat dome — a high pressure system that pushes hot air down and traps it — that is becoming more common and intense as a result of climate change.

Flash floods wreak havoc on the Midwest

After days of heavy rain last week, flash floods emerged, inundating towns in Iowa, South Dakota and Minnesota. The governors of all three states issued disaster proclamations on Saturday in response to the deluge.

In Iowa, the northwest region was especially hit hard. Troves of residents were forced to evacuate, major roads were closed, and local water and power lines were damaged. On Sunday, officials from Rock Valley said the city was still struggling to access clean water.

In Minnesota, the state's National Guard was deployed after some towns were submerged in a foot of water. In Waterville, about an hour south of Minneapolis, floodwaters reached between 14 to 18 inches and residents were ordered to evacuate.

South Dakota also faced severe flooding this weekend, but the Gov. Kristi Noem said Saturday that she anticipates the worst flooding to occur on Monday and Tuesday. The concern is related to the state's rivers, which are expected to rise to record levels early next week.

All three states were still under a flood warning as of Sunday afternoon.

Severe thunderstorms form in the Northeast

Severe storms are underway in the Northeast, possibly producing large hail, damaging winds and isolated tornadoes.

The areas at risk of dangerous thunderstorms include New York City, Montauk, Stony Brook in New York; Newark, Elizabeth, and Paterson in New Jersey; and New Haven, Waterbury and New London in Connecticut.

A tornado watch was issued for parts of southwest and western Maine; as well as multiple counties in central, northern and southern New Hampshire.

Meanwhile, an excessive heat warning remains in effect until Sunday night in parts of northern Delaware; central, northern and southern New Jersey, and southeast Pennsylvania.

According to NWS Mount Holly, Philadelphia and Reading broke daily highs on Sunday after surpassing 97 degrees as of 2 p.m. On Saturday, Reading reached a high of 101 degrees — becoming the first time the city reached triple digits since 2012.

Triple digit heat arrives in the South

The heat wave is expected to reach the South by Monday — producing triple digits in the day and mid-70s at night.

Already, some parts of Mississippi experienced heat indexes of 105 to 110 degrees on Sunday and the scorching temperatures will last through Tuesday, NWS Jackson said. (Heat indexes measure what the weather actually feels like when you account for both the temperature and humidity.)

Similarly, in middle Tennessee, the heat index is forecast to exceed 100 degrees from Sunday to Tuesday, according to NWS Nashville.

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