A widespread, searing heat dome and an extreme fire threat are expected as a major US weather pattern change unfolds

By Meteorologist Chris Dolce, CNN

(CNN) — A heat dome will bring dangerously hot and humid conditions to the eastern half of the United States next week in the region’s most widespread heat wave of the summer so far.

The heat dome will build in response to a large shift in the jet stream that’s also bringing a big cooldown to the West. Powerful winds will accompany the cooldown and intensify already dangerous fire weather conditions in Utah, where a large, destructive fire is ongoing, and in neighboring states.

Major cities including Chicago, Detroit, St. Louis, Dallas and Nashville could see thermometers climb to their highest level yet this year by early next week. Conditions will be made more oppressive by a big surge of humid air spreading out of the South into the Midwest. The sultry weather pattern will then expand eastward to the Northeast by midweek.

The heat index, or what it feels like with humidity factored in, will soar to hazardous levels across this wide area as the heat dome stagnates and traps hot air for days. Millions will see their so-called “feels-like” temperature hit 100 to 110 degrees; some places will peak as high as 115 degrees.

Heat waves worldwide are becoming more harsh and frequent because of human-caused warming from fossil fuel pollution. The record-shattering heat waves in Europe this past week and in the western US in March are two recent examples.

This upcoming heat wave won’t rival those when it comes record-breaking extremes in most areas, but it will be scorching for days and no less dangerous.

Major to extreme heat risk ahead

Heat and humidity will intensify in the South this weekend and then expand northward toward the Midwest and Great Lakes by early next week. Parts of the Northeast will feel increasingly hot and humid by Tuesday or Wednesday, including New York City, Pittsburgh, Pennsylvania, and Washington, DC.

High temperatures in the upper 90s to near 100 degrees will grip a large area of the South, and highs in the low to mid-90s will be commonplace in the Midwest and parts of the Mid-Atlantic and Northeast. A World Cup match at New York New Jersey Stadium on Tuesday at 5 p.m. ET could start out a bit sweltering with a temperature in the upper 80s and a heat index in the lower 90s.

Tens of millions of people are in a Level 3 of 4 “major” or Level 4 of 4 “extreme” heat risk from the Deep South to as far north as parts of Minnesota, Wisconsin and Michigan and as far east as New York and the Mid-Atlantic on one or more days next week, according to the National Weather Service.

Heat this severe can affect anyone without proper cooling or hydration, according to the weather service. Little relief is expected at night, since high humidity will prevent temperatures from cooling much.

Low temperatures next week won’t fall below the lower-to-middle 70s in the Midwest and Great Lakes. Urban areas could struggle to fall much below 80 degrees.

Prolonged exposure to extreme heat can cause illnesses like heat exhaustion, heat cramps, and the most serious type, heat stroke, according to the US Centers for Disease Control and Prevention. Emergency room visits for heat-related illness surge on “major” and “extreme” risk days, according to the National Weather Service.

Heat is also the deadliest type of weather in the US, with a higher annual average death toll than tornadoes, hurricanes and lightning combined, according to weather service statistics.

Exactly how long next week’s heat dome will stick around is still uncertain, but it could begin to shift west toward the Plains over the Fourth of July weekend. Hot and sticky weather will persist in the South, but could ease up a little for the Midwest, Great Lakes and Northeast during the holiday weekend or just after its over.

This first widespread heat wave is happening right as the central and eastern US begin to enter their usual hottest time of year.

Most of these areas see their average warmest day in July, while the Southern Plains and Lower Mississippi Valley usually experience peak heat in August, according to the National Centers for Environmental Information.

‘Particularly dangerous’ fire weather in Utah

A Level 3 of 3 risk of extremely critical fire weather conditions has been issued for Friday in fire-plagued Utah as well as nearby parts of northern Arizona and eastern Nevada.

The threat is so severe it prompted the first-ever “particularly dangerous situation” red flag warning from the National Weather Service office in Salt Lake City. It includes central and southern Utah and the Cottonwood Fire, the state’s current largest inferno. This exceptionally rare designation is reserved for the most extreme fire weather conditions.

“This is a Particularly Dangerous Situation that poses a significant threat to life and property in the event of a wildfire start or with an existing fire,” the warning said. “In some cases, safe and timely evacuation may not be possible should a fire approach.”

Wind gusts up to 50 mph could fan both ongoing fires and any new fires that sprout up.

Several large wildfires continue to burn across central and southern Utah. The Cottonwood Fire, east of Beaver, Utah, has burned through an area roughly the size of Salt Lake City in just a few days and remains 0% contained. Evacuations are in place for the fire, which state and local officials believe is likely Utah’s most destructive and costly wildfire on record.

Damage assessments are planned or ongoing, so the total number of structures destroyed by the fire is unknown. The most destructive fire in Utah history was 2018’s Dollar Ridge Fire which destroyed 74 homes, according to Karl Hunt, public affairs officer with the Utah Division of Forestry, Fire, and State Lands.

Farther north, the Iron Fire near Eureka, Utah, has burned more than 40,000 acres after forcing evacuations earlier this week.

Fire danger will remain high in much of the same region on Saturday as gusty winds and low humidity persist.

The-CNN-Wire
™ & © 2026 Cable News Network, Inc., a Warner Bros. Discovery Company. All rights reserved.

CNN Meteorologist Briana Waxman and CNN’s Kate S. Petersen contributed to this report.