The Big Hot Bubble: A Simple Guide to the U.S. Heat Wave

What Is Going On?

A huge and dangerous heat wave is growing across the United States. Think of it like a super-hot blanket covering the country.

• On Saturday, a heat wave was building.
• Triple-digit temperatures (that means over 100°F / 38°C) are expected in the Southwest and Great Plains this weekend.
• It will then move eastward, trapped under a big "dome" of heavy air.
• Weather scientists (meteorologists) say this dome could keep temperatures oppressively hot for a week or more.
• The hot dome might affect as much as two-thirds of the continental U.S. (the lower 48 states, not counting Alaska or Hawaii).

Important: Forecasters say temperatures will be 15 to 25°F (8 to 14°C) warmer than normal in many places — even at night! This is especially bad for our bodies because we need cooler nights to recover.

Why Is It Called a "Heat Dome"?

A heat dome forms when a big pile of heavy air (called high pressure) sits on top of the land. This heavy air acts like a lid on a pot:

• It traps hot air underneath.
• It blocks cool winds from blowing in.
• It stops rain from falling, which would normally cool things down.

Chad Merrill, a senior weather scientist at AccuWeather, said this dome is one of the strongest to hit the Dakotas in 25 years.

Voices from the Ground

Josh Adam, a weather scientist in North Dakota, said: “The heat doesn’t necessarily stop when it’s dark out.” In his state, temperatures will stay above 100°F (37°C) until Tuesday — a big jump for a place where summer is usually in the 80s°F (about 27–32°C).

Tynika Smith from Bloomington, Minnesota, is helping people who live outside in tents near St. Paul. She handed out:

• Frozen towels and washcloths
• Battery-operated fans
• Water, freezer pops, food, and hygiene supplies

Next week, when temperatures climb to the mid- to high 90s°F (around 35–37°C), she will keep helping. The homeless neighbors put ice packs on their necks and heads. Smith said they can’t go into an air-conditioned car or house, and the tent camps are hidden far from cooling centers. Inside tents, it’s even hotter than outside. “I can only do so much,” she said, “but at least I can help them stay cool for a little bit.”

Temperature Records Ready to Fall

The National Weather Service predicts that more than 90 local temperature records will be tied or broken by Wednesday. Two-thirds of those are for overnight heat!

Cities where nighttime temperatures won’t drop below 80°F (27°C):

• Fort Lauderdale, Florida
• Miami, Florida
• Tampa, Florida
• Galveston, Texas
• Charleston, South Carolina

Record triple-digit highs are expected this weekend in:

• Nevada
• Utah
• Colorado
• Wyoming
• Idaho
• Montana
• The Dakotas

In Helena, Montana, where it’s usually about 85–90°F in June/July, temperatures may hit 95°F (35°C). A local pool called Last Chance Splash held a swim meet there. Assistant manager Sean Swingley said the pool is nice and cool, even if the day is hot, and it’s uncommon for Helena to get so hot.

In Las Vegas, Nevada, meteorologist Andrew Gorelow said Saturday could hit 111°F (48°C) — even hotter than their normal hot weather.

How to Stay Safe: Easy Steps

Experts say keeping your body cool and drinking water is super important. Here are simple steps:

1. Drink plenty of water (hydrate!) even if you’re not thirsty.
2. Find a cool place — like an air-conditioned room, library, or cooling center.
3. Help neighbors who might not have AC, especially older people or those without homes.
4. Watch for fire danger — the hot, dry conditions (like in the Rocky Mountains) can make wildfires more likely. Strange "dry thunderstorms" (lightning without much rain) could spark fires.

Important: If you feel dizzy, super tired, or sick from heat, tell an adult and get to a cool place fast.

Why Is the Heat Getting Worse? Climate Change & El Niño

Two big reasons make heat waves like this stronger:

• Climate change: This is caused by humans burning coal, oil, and natural gas. It acts like a thick extra blanket around Earth, making heat waves more intense, longer, and bigger.
• El Niño: This is a natural warming of the ocean water near the equator (the middle of Earth). It changes wind and weather patterns and pushes global temperatures up.

The current El Niño formed last month. It’s too new to have caused this specific heat wave, but experts say it may become one of the strongest since records began in 1950. By fall, there’s an 81% chance it becomes "very strong" (the top level) according to the U.S. National Oceanic and Atmospheric Administration (NOAA).

Summary

A giant heat dome is covering much of the United States, bringing temperatures 15–25°F above normal, even at night. It may break over 90 temperature records, hurt people without homes, and raise fire risk. The heat is made worse by climate change and a new El Niño. Drink water, find cool spots, and check on friends to stay safe.

FAQ

Q1: What is a heat dome in kid words?
A: Imagine a giant invisible lid made of heavy air sitting on the country. It traps hot air inside like a pot with a lid, so the heat can’t escape and no cool breeze comes in.

Q2: Why is hot weather at night so dangerous?
A: Our bodies need cooler nights to rest and recover from daytime heat. If it stays above 80°F all night, our bodies can’t cool down, which can make people very sick.

Q3: How can I help during a heat wave?
A: You can share water, frozen towels, or battery fans with people who don’t have air conditioning. You can also check on elderly neighbors and remind everyone to drink water.

Q4: What is El Niño and why does it matter?
A: El Niño is when the ocean near the equator gets warmer than usual. This shifts weather worldwide and makes overall temperatures higher, adding a bit more heat on top of climate change.

Q5: Will the heat last a long time?
A: Meteorologists say the dome could trap heat for a week or more, and nighttime records may fall through Wednesday, with some areas staying super hot into next week.