A weather expert has issued a warning over a looming ‘mega heat dome’ expected to bring intense temperatures to the US heading into the Fourth of July holiday period.
Forecasters say the eastern half of the country could be hit especially hard, with North Carolina among the areas expected to face some of the most oppressive heat and humidity.
A heat dome develops when a strong area of high pressure settles over a region and traps hot air beneath it.
Because that air is unable to move away easily, temperatures can keep climbing and create a prolonged stretch of extreme heat.
This setup can act like a lid over the atmosphere, allowing heat to build at the surface and sometimes keeping nighttime temperatures uncomfortably high as well.
Current forecasts suggest the heat dome will spread across broad areas of the central and eastern US in the run-up to Independence Day, with the most intense conditions likely to build from the weekend into next week.
Meteorologist Ryan Maue said on social media that North Carolina is expected to see some of the most severe conditions.
Taking to X, he wrote: “North Carolina will be ground zero for the upcoming ‘mega heat dome’ over the Eastern US into the July 4th weekend.”
By the middle of next week, temperatures in the 90s are forecast for much of the central and eastern US, with some locations expected to reach the low 100s.
NOAA forecasters say the combination of heat and humidity could push heat index values to around 105F to 110F in many places, which can make conditions feel far more dangerous than the thermometer alone suggests.
AccuWeather has also warned that late June and early July will bring a multi-day heat wave across the Plains, Midwest and East, with little overnight relief in some cities.
When humidity is factored in, it could feel even hotter in parts of the Southeast and lower Mississippi Valley.
AccuWeather meteorologists have cautioned that the Fourth of July weekend could bring widespread dangerous heat across parts of the US.
Alex Sosnowski is a meteorologist with AccuWeather, and said in a statement shared with the Daily Mail: “A multiday heat wave is brewing across the middle of the nation ahead of the Fourth of July weekend, expanding from the Plains to the Midwest and even nosing into the East.”
One reason heat domes become so intense is that sinking air compresses and warms as it moves downward.
That can make already hot conditions even more punishing, especially when moist air is trapped in place and prevents cooling overnight.
The National Weather Service uses the heat index to describe when temperatures may become dangerous.
The index shows how air temperature and humidity combine, meaning even a lower reading on the thermometer can feel much hotter and still pose a serious health risk.
Officials warn that prolonged exposure to extreme heat can lead to dehydration, heat exhaustion and heat stroke, especially for children, older adults, outdoor workers and anyone without reliable access to cooling.
Experts say people should drink plenty of water, avoid strenuous activity during the hottest part of the day and check on vulnerable neighbours, relatives and pets as the heat wave intensifies.