Extreme Heat Sweeps Across the U.S.: Millions Under Threat”

A powerful heat wave is sweeping across much of the United States, especially in the Midwest, the Southeast, and up along the East Coast. This heat wave is being driven by a heat dome, a weather pattern that traps hot air in one place for many days. With temperatures often soaring over 100 °F (38 °C) and humidity adding to the heat, this situation is putting millions of people at serious risk.

What’s Going On?

The National Weather Service (NWS) has issued Extreme Heat Warnings and Heat Advisories across 11 to 18 states, depending on the region. At least 185 million people are affected, and in some areas the number reaches nearly 200 million.

Temperatures are not just high—they’re dangerous. The heat index, or the "feels-like" temperature when humidity is added, is hitting 110–115 °F, and in a few places it could even reach 120 °F . Cities like St. Louis, Memphis, Baton Rouge, New Orleans, Jacksonville, Raleigh, and Des Moines are under the strongest warnings.

For example:

Tampa, Florida hit 100 °F for the very first time and broke its daily record. The heat index there has reached 113 °F.

.In states like Iowa, Missouri, Kentucky, South Carolina, Tennessee, and Nebraska, the heat index could exceed 115 °F.

This extreme heat is expected to last through midweek, although some relief is possible later in the week as cooler air moves in, especially in parts of the Northeast and Great Lakes regions.

Why This Heat Is So Dangerous

1. The Heat Dome

A stable, high-pressure system in the upper atmosphere traps hot air beneath it—this is called a heat dome. It doesn’t move or break easily, so the heat just keeps building. With clarity in the sky and lots of sunshine, temperatures climb day after day.

2. Humidity and “Corn Sweat”

High humidity makes the heat feel much worse. In the Corn Belt region, farm fields release moisture, increasing humidity even more. This is called corn sweat, and it can boost the “feels-like” temperature by several degrees.

3. Little Overnight Cooling

Usually, nighttime brings relief. But this time, overnight temperatures stay high—often in the 70s °F or more—so the body never gets a break. Heat builds day after day, increasing risk of illness.

Who Is at Risk?

Heat is the leading cause of weather-related death in the U.S., with around 2,000 lives lost each year, according to the CDC

In 2025 alone, about 150 heat-related deaths have already happened—with final numbers likely higher once all data is in.

Some groups are especially vulnerable:

• Older people
• Young children
• People with chronic illnesses
• Outdoor workers
• People in low-income communities, often with little access to cooling

What You Need to Do to Stay Safe

Here are simple steps everyone should take when facing Extreme Heat:

1. Stay in air-conditioned places as much as possible—at home, or in cooling centers, malls, or libraries.
2. Drink plenty of water, even if you're not thirsty. Avoid alcohol and sugary drinks—they can make dehydration worse.
3. Avoid sun exposure especially from 12 p.m. to 4 p.m.
4. Wear light, loose clothing and take frequent breaks in the shade if outdoors.
5. Never leave children or pets in a parked car, even for a few minutes—inside temperatures rise very fast
6. Know the signs of heat illnesses:

• Muscle cramps, heavy sweating
• Dizziness, nausea, shortness of breath
• Weakness or confusion

• If these symptoms don’t get better after cooling down and hydrating, get medical help right away

1. Check on nearby people, especially those who may not have air conditioning or live alone

What Cities and Regions Are Most Affected?

• Midwest and Corn Belt: Iowa, Missouri, Illinois, Nebraska—heat index over 110–115 °F.
• Southeast and Gulf Coast: Florida, Mississippi, Louisiana—extreme heat warnings remain in effect.
• East Coast and Mid‑Atlantic: Cities like Washington, D.C., Philadelphia, Baltimore, Boston, New York—some days hitting 99–103 °F with high humidity
• Tampa, FL: Broke long-standing record with a reading of 100 °F, with feels-like temps at 113 °F.

In total, extreme heat alerts cover 11 to 18 states, and in some places nearly half of the U.S. population is under heat-related warnings or advisories

When Will It Ease?

Relief is expected later in the week, as cooler air moves in from the north. Temperatures may drop by 10 to 20 °F in the Great Lakes and Northeast, with nights cooling off into the 60s or 70s °F—finally offering some respite from the overnight heat

Bottom Line

This extreme heat wave is breaking records and pushing safety limits across much of the United States. A heat dome is trapping hot and humid air. Many people do not get enough rest at night because temperatures stay high. Health risks are real. To stay safe:

• Stay cool indoors,

• Drink water,
• Avoid peak sun hours,
• Dress lightly,
• And watch your neighbors.

This heat is serious—but if we take smart steps, we can protect ourselves and our communities.