The Giant Hot Lid: A Simple Explanation of the U.S. Heat Wave

What Is Going On?

• About 100 million people in the United States are feeling very, very hot temperatures this week.
• A weather thing called a heat dome (think of it like a giant invisible pot lid that keeps hot air stuck in one place) started in the western part of the country and is now moving to the Northeast.
• On Sunday, in Billings, Montana, it got as hot as 111°F (that’s about 44°C), which is a new record high. The dangerous heat was also felt across the Great Basin, the Rocky Mountains, and parts of the desert Southwest.

Maps Show the Latest Heat Wave

Weather forecasters use maps to show where it will be hottest. Here is what they tell us:

• Temperatures are expected to be 20 to 30 degrees hotter than normal for this time of year, according to CBS News meteorologist Nikki Nolan.
• Some places will see record-breaking temperatures all week.
• One map shows forecast high temperatures and heat alerts stretching from the Plains to the Northeast.
• Another map shows the “heat index” (that’s how hot it feels when you mix the air temperature with sticky humidity) from the northern Plains through the Northeast.
• A third map shows which areas are forecast to see above-normal temperatures in mid-July 2026.
• The hottest day for the Northern Tier (the top part of the country) is expected on Tuesday. For the Northeast, the peak is Wednesday.
• For the next several days, the heat index will be in the high 90s to over 100 (that’s super hot and sticky!).

Records Breaking and Big Warnings

• Salt Lake City reached an all-time high of 109°F on Sunday. The old record was 107°F, which had been tied in 1960, 2002, 2021, and twice in 2022.
• Most of Utah was under an extreme heat warning (a special alert that says “stay safe, it’s dangerously hot”) until Tuesday morning.
• The Dakotas (two states in the north) also got warnings for extreme heat.
• Forecasters say this long period of heat is “exceptionally rare” for some locations, even in mid-July.
• The National Weather Service says the hazardous heat will move eastward at times and will stay in the central part of the country through next weekend.

Important Point: Extremely hot daytime highs combined with potentially record-warm nighttime lows will result in increasing heat stress over the next several days because our bodies get limited relief. This can cause sickness like heat stroke. Drink water and stay cool!

Why Is This Happening? The Heat Dome

• A heat dome is an atmospheric phenomenon (a fancy way of saying “something that happens in the sky”) that essentially traps hot air over a particular location.
• It built up in the West after the first heat wave of the summer began to bake the area last week.
• Forecasters say we should get ready for widespread temperatures between 105°F and 115°F, breaking many local records.
• This heat also increases wildfire risks and raises the chance of heat-related illnesses.

Heat Fuels Wildfires and Strong Thunderstorms

Hot weather can act like fuel for fires and big storms.

• In California, the Summit Fire near Antelope Valley (outside Los Angeles) made people evacuate (leave their homes) for a while. It burned nearly 3,000 acres of land. By Sunday evening, firefighters had it 31% contained (meaning they stopped its spread a bit).
• Extreme heat is expected in Southern California and Arizona through Thursday, with temperatures in the 90s and 100s, especially in the desert Southwest. Southern California might even break overnight heat records, but the Southwest isn’t expected to break those.
• In Colorado, two new wildfires started on Sunday in the high country. Firefighters are also still fighting the Aspen Acres Fire, which has burned more than 850 structures, including hundreds of homes.
• Senator John Hickenlooper (a Colorado Democrat) visited the damage and said the state needs more money to fight wildfires because there have been huge cuts to the fire service and the Bureau of Land Management (the group that manages public lands).

Rain and Flood Risk in Other Places

While some places are super dry and hot, others are getting too much water!

• In the South, heavy rain and flooding are a worry. In Louisiana, thunderstorms dropped several inches of rain on New Orleans, and families had to walk through knee-high water.
• On Saturday, Missouri had historic flash flooding (when rain comes so fast it floods quickly). Rescue crews used helicopters to lift more than 200 people (including kids at a children’s camp) after 6 to 12 inches of rain fell in the southeastern part of the state.
• Farther east, near Philadelphia, powerful microbursts (sudden, strong wind blasts from a storm, like a giant sneeze from a cloud) hit with gusts up to 70 miles per hour. Mayor Cherelle Parker signed a Declaration of Disaster Emergency on Sunday.

Summary

Let’s recap the big points:

• Around 100 million Americans are under a heat dome causing record-breaking heat (105–115°F expected).
• Places like Montana, Utah, and the Dakotas set records and have extreme heat warnings.
• The heat peaks Tuesday (North) and Wednesday (Northeast) and lingers through next weekend in the central U.S.
• Wildfires are burning in California and Colorado, worsened by the heat.
• The South and Midwest face heavy rain, flooding, and strong winds.
• Stay safe: drink water, cool down, and heed warnings.

FAQ

Q1: What is a heat dome in kid terms?
A: Imagine a giant invisible lid on a pot. The pot is the ground, and the heat is the steam. The lid keeps the hot air from escaping, so the place under it gets super hot.

Q2: What does “heat index” mean?
A: It’s how hot it really feels on your skin when you mix the actual temperature with the stickiness (humidity) in the air. So 90°F with lots of moisture can feel like 100°F.

Q3: Why are wildfires happening because of the heat?
A: Hot weather dries out plants and trees, making them like tiny pieces of paper. A small spark can then turn into a big fire very fast.

Q4: What is a microburst?
A: It’s a sudden blast of wind from a thunderstorm that pushes down to the ground. It can be as strong as a tornado for a short time, knocking things over.

Q5: How can I stay safe during this weird weather?
A: Drink plenty of water, stay indoors during peak heat, listen to local alerts, and if you live where there is flooding, move to higher ground.

This article is based on reporting by Carter Evans, Nikki Nolan, and Andrew Kozak for CBS News.