Swelter Alert: Heat Dome Grips South, Midwest, and Northeast in July 2025

By July 23, 2025, extreme heat will swelter millions across the United States, with parts of the South, Midwest and Northeast experiencing triple-digit heat indexes. Nearly 60 million people have been issued heat warnings, and the forecast shows this extreme heat wave is unlikely to end anytime soon. Here's what you need to know about this extreme heat, its effects and how to avoid it.

Swelter Alert: Heat dome grips U.S. with triple-digit heat indices.

What’s Fueling This Extreme Heat Wave

A heat dome—a high-pressure system that traps hot air—has become stationary over the central U.S., pushing temperatures from the mid-90s to the low-100s Fahrenheit (35-40 degrees Celsius). High humidity is making it even worse, with places like Memphis, Atlanta and St. Louis seeing heat index values reach 110-115 degrees Fahrenheit. Centered over the Mississippi Valley, this oppressive weather pattern is affecting the South, Midwest and now the Northeast, where cities like New York and Philadelphia are set to face extreme heat on July 25.

Where Is the Heat Wave Hitting Hardest

South and Mississippi Valley: Relentless Heat and Humidity

The heat continues to rage in the South, where nighttime temperatures have hit record lows and temperatures have soared above 70 degrees, but there's no significant respite. Temperatures could reach 115°F in cities across the Corn Belt, Southeast and Mid-South, posing a serious risk to those without air conditioning.

Midwest and Ohio Valley: Feeling the Burn

The Midwest region, including Chicago and Detroit, is grappling with more hot and humid air. The Ohio Valley and Great Lakes regions are under heatwave warnings, with temperatures expected to be 10-15°F above average. Lack of cooling at night is a growing concern for vulnerable populations.

Northeast: A Short but Intense Heat Spike

heatwave will peak in the Northeast on Friday, July 25, particularly along the I-95 corridor (Boston, New York City, Philadelphia). Maximum temperatures are expected to be near 100°F and heat indexes above 100°F, although a cooler air mass may bring some relief to the upper Midwest and Great Lakes by the weekend.

Why This Heat Wave Feels So Extreme

According to Climate Central, climate change has increased the likelihood of such heat waves by three to five times. From Salt Lake City to Tallahassee, nearly 160 million Americans are facing increasing threats from human-caused heat. The summer of 2025 already ranks among the top 10 hottest for many eastern U.S. cities, with the Northeast , Mid-Atlantic and Midwest seeing unprecedented heat.

How to Stay Safe During the Heat Wave

Since heat-related illnesses are the leading cause of weather-related deaths in the U.S., here are some important tips to stay safe:

• Stay hydrated : Drink plenty of water, even if you're not thirsty.

• Seek cool places : Use air-conditioned areas like the mall or library if your home lacks cooling.

• Avoid extreme heat : Limit outdoor activities between 10 a.m. and 4 p.m.

• Watch others : Keep an eye on elderly neighbors, children or people with health problems.

• Know the signs : Watch for symptoms like dizziness, nausea or muscle cramps and move to a cooler place if they appear.

With the power grid under pressure, electric distribution companies like Duke Energy Carolina are maximizing generation to meet demand. If you're in an affected area, conserve energy where you can to reduce load.

What’s Next for the Weather Forecast

The heatwave is expected to last through the last weekend of July across the South and Plains, possibly spreading westward toward the Rockies. The Northeast may see some relief this weekend, with showers and thunderstorms, but humidity will remain high. Western states like Salt Lake City and Boise could see temperatures reach 100°F by early August.