The United States is bracing for the country’s “third major heat dome” in the past month, reported The Guardian. Forecasters warned that dangerous temperatures could affect up to 80 million people across the South, Great Plains and parts of the Midwest, according to AP and The Guardian reports. Forecasters have warned that the intense heat is likely to persist through much of the coming week, increasing the risk of heat-related illnesses.
The US National Weather Service has issued excessive heat warnings and advisories across several states as temperatures climb well above seasonal averages. Meteorologists say this latest heat dome is expected to remain nearly stationary for several days, trapping hot air over the region and preventing temperatures from falling significantly even at night.
“The overnight lows are not expected to come down enough for people to have much chance to recover,” reported AP quoting forecasters as saying. High humidity is also making conditions feel much hotter than the actual air temperature.
Which US states are likely to be affected?
The heat dome covers a vast area of the country. The worst conditions are expected across Texas, Oklahoma, Kansas, Nebraska, South Dakota, North Dakota, Colorado, Wyoming, Montana, New Mexico, Arkansas, Louisiana, Mississippi and parts of the Midwest and Great Plains, reported AP.
Extreme heat warnings have already been issued for parts of western Nebraska, where temperatures could reach 108 degree Fahrenheit (42 degree Celsius). Forecasters also expect temperatures above 100 degree Fahrenheit (37 degree Celsius) in areas of Montana and Wyoming that usually experience much milder summer weather, according to AP report.
The heat is also affecting major cities across the South and Southwest. Dallas remains under dangerous conditions, while Las Vegas could come close to record-breaking temperatures. In the Denver area, temperatures are expected to stay 10 to 15 degree Fahrenheit above normal, with some daily records at risk.
“It looks like it is going to be pretty much stationary in that position as we go through the week,” National Weather Service meteorologist Bob Oravec told AP. Some parts of the country may avoid the worst of the heat. Forecasters expect much of the Northeast, the Mid-Atlantic and the Pacific Northwest to escape the most dangerous temperatures.
Why is this heat dome dangerous?
A heat dome forms when a strong area of high pressure traps hot air close to the ground for several days. The trapped air continues to warm under clear skies, while weak winds prevent cooler air from entering the region. This leads to prolonged periods of extreme heat.
Meteorologists say the biggest concern is that temperatures will remain unusually high even after sunset. Warm nights prevent the human body from cooling down, increasing the risk of dehydration, heat exhaustion and heat stroke, reported AP.
Health officials have urged people to stay indoors in air-conditioned spaces whenever possible, drink plenty of water and avoid strenuous outdoor activities during the hottest part of the day. Older adults, young children and people with existing medical conditions face the greatest risk from prolonged exposure to extreme heat.
Meteorologists expect the worst heat to shift toward Texas and parts of the Gulf Coast by the middle of the week, although some relief may reach parts of the central United States next weekend. However, forecasters warn that any cooling could be temporary.
The latest heat dome follows two other major heat events that affected the United States earlier this summer. An intense early July heat wave disrupted Independence Day celebrations across several communities, while another round of extreme temperatures struck the Southwest and Great Plains later in the month.
Scientists say it is difficult to directly link a single weather event to climate change. However, rising global temperatures caused by greenhouse gas emissions have increased the likelihood of more frequent and more intense heat waves.
“We are experiencing exactly what the climate models in the 1990s said we should experience now,” Andy Pershing, chief program officer at Climate Central, told AP. “That is more frequent, more severe heat waves, bigger temperature anomalies, more humidity, higher overnight temperatures. These are all part and parcel of the climate story.”
According to the National Centers for Environmental Information, the continental United States recorded its second-hottest first half of the year in 2026.