By midafternoon on summer days, North Carolina heat can turn ordinary routines into second thoughts: Is the concrete too hot for the dog? Can the grass wait to be cut? Is it safe to walk to the mail, or should the kids’ practice move indoors?
When the air is both hot and humid, the body can’t cool itself as easily. And during a heat dome, the discomfort can last for days.
What is a heat dome?
A heat dome is a meteorological phenomenon that happens when a large area of high pressure in the atmosphere settles over a region and holds hot air in place. Scientists say a heat dome is like a lid over a pot. The air beneath it sinks, compresses, and warms.
At the same time, high pressure can limit cloud cover and steer rain-producing storms away. With more sun and fewer cooling breaks, temperatures often climb and remain high for several days.
That’s why heat domes don’t always mean one record-breaking afternoon. In many cases, the bigger problem is a long stretch of hot afternoon air followed by a night that does not cool off enough. According to the North Carolina Department of Environmental Quality, people sleeping overnight in temperatures at or above 70 degrees Fahrenheit, are at a higher risk of experiencing a heat-related illness.
Why it feels worse in NC
North Carolina’s heat is often humid.
Normally, sweat cools the body as it evaporates. The body responds by sending more blood toward the skin to shed heat. But when the air is already full of moisture, sweat evaporates more slowly and the body has to work harder to release heat, which is why a 90-degree Fahrenheit day with high humidity can feel much more punishing than a dry day with the same temperatures. That’s where the heat index comes in.
The heat index combines air temperature and humidity to estimate how hot conditions will feel to the body. So when the forecast says it will be 94 degrees Fahrenheit but “feels like” 104, the second number is the one to take seriously.
How heat domes raise the risk
Heat domes can affect more than the temperature on weather apps. In practical terms, they can mean hotter pavement, cars, and playground equipment; higher rates of air-conditioning use, inflated electric bills, and less relief for outdoor workers; along with added risk for older adults, young children, and people with health conditions.
With risk building over time, a person may feel fine after a hot day—but several days of heat, especially when nights remain warm, can make dehydration, heat exhaustion, and heat illness more likely. In cases where a heat illness is suspected, state health officials urge residents to call 911.
Where climate change comes in
A heat dome is a weather pattern, but climate change makes the heat it traps more dangerous. In the case of North Carolina, a heat dome has formed over a state where average midsummer temperatures are already hotter than they were several decades ago.
According to Climate Central’s analysis of the National Oceanic and Atmospheric Administration (NOAA) temperature records, Charlotte’s average July temperature rose 3.2 degrees between 1970 and 2025. In the Raleigh-Durham area, average July temperatures rose 4.9 degrees over the same period.
A few degrees can change what a heat wave feels like, and how long people, homes, and neighborhoods have to recover after a hot day. Research on the June 2021 Pacific Northwest heat wave shows what happens when a heat dome develops in an already warmer climate.
In a peer-reviewed study by Earth System Dynamics, an international team of climate scientists compared that event with the pre-industrial climate of 1850-1900. They found that “such a heat wave event would be at least 150 times less common without human-induced climate change,” and about 2 degrees Celsius less hot—which is about 3.6 degrees Fahrenheit cooler.
That does not mean every dome is 150 times more likely to have occurred solely because of climate change, or that the Pacific Northwest finding can be applied directly to North Carolina. But it does show how a warmer climate can make an already unusual high-pressure event much more severe.
What North Carolinians can do
The simplest rule is to make plans around the heat instead of trying to push through it.
ReadyNC, the state’s emergency preparedness website, advises residents to check local forecasts and pay attention to the heat index. Full sunshine can make the heat index feel as much as 15 degrees higher. When that number climbs, postpone strenuous activities, outdoor games, and exercise when possible, or move them to the early morning or late evening.
If being outdoors is avoidable, wear lightweight, loose-fitting, and light-colored clothing, cover your head with a wide-brimmed hat, and take frequent breaks in the shade or air conditioning. Health officials also recommend drinking water regularly, even before feelings of thirst, and limiting alcohol.
If air conditioning is not available at home, ReadyNC recommends spending the warmest part of the day indoors in a public building such as a library, school, movie theater, shopping center, or other community space with cooling. During a power outage, residents can text SHELTER and their ZIP code to 43362 to find a nearby shelter, or use 211.org to look for cooling centers.
