These unbearably hot and humid summer months, which put millions of people around the world at risk, are often made possible by phenomena known as heat domes.
Heat domes can make already high temperatures even more extreme and prolonged; Its intensity is getting worse and its frequency increases as the planet warms.
This is what you need to know.
What makes up a heat dome and what does it do?
Heat domes are essentially high-pressure systems that hover over a region and trap heat and moisture, experts say.
They originate from the northward flow of warm air. This system causes the air to descend, increase the pressure and increase the temperatures.
“The concept of a heat dome really means that the air in this region is very warm, and we know that warm air expands,” explained Jennifer Francis, a climatologist at the Woodwell Climate Research Center. “Basically, this means that the layers of the atmosphere also bulge upward.”
Simply put, heat domes cause heat waves, experts say.
How has the heat affected the world this year?
The heat affected various regions of the world at the beginning of 2026.
The continental United States in March recorded its most abnormally warm month in 132 years of records, with record-breaking extremes first in the Southwest and then across the rest of the country. The heat affected the French Open and punished parts of India in May. Since then, extreme heat has been a central concern for the soccer World Cup taking place in the United States, Canada and Mexico.
Europe has been scorched since mid-June under unusual high temperatures of around 40 degrees Celsius (104 Fahrenheit) in many places due to a heat dome.
Now, much of the eastern United States is expected to experience a long heat wave in the coming days, and already this week, much of the Southwest is seeing temperatures around 100°F (38°C), and those temperatures could spread elsewhere by the July 4 holiday.
What role does climate change play?
Science shows that as the planet warms—as a result of humans burning coal, oil, and gas—heat waves get worse, last longer, and become more frequent.
“Heat waves like this are directly linked to the climate crisis and climate change,” Francis said. “And it’s because of the way we’ve burned fossil fuels and cut down forests for so long, increasing the concentration of heat-trapping gases in the atmosphere,” he added.
“These types of heat waves and droughts, and the fires associated with them, are increasing just as we would expect them to in a warming world,” he added.
How can I stay safe?
Experts say people need to stay hydrated when the heat and humidity hits. Heat domes can make it difficult to fully recover from high temperatures at night, so it’s important to find ways to stay cool during the day and into the evening hours.
Be sure to avoid exercising outdoors during the heat of the day — and seek shade or, if you can, access to air conditioning. Some cities offer resources and cooling centers to provide relief.
Cooling off in nearby pools or bodies of water can also help.
This story was translated from English to Spanish with an artificial intelligence tool and was reviewed by an editor before publication.