Asger Risom
Heat domes trap extreme heat over regions for days or weeks, intensifying health risks and raising urgent questions as climate change makes them more frequent.
As temperatures rise globally, so do the rare but dangerous weather patterns known as heat domes.
These persistent high-pressure systems can linger over populated areas, trapping sweltering air like a lid on a boiling pot.
With climate models showing they’re becoming more frequent and intense, understanding their formation, impact, and prevention has never been more crucial.
What exactly is a heat dome?
A heat dome forms when a high-pressure system stalls over land, preventing hot air from escaping or cooler weather from moving in. According to meteorologist Eric Kelsey, quoted in Popular Science, it’s “a large area of warm air… associated with high pressure” that can linger long enough to cause significant health impacts.
The lack of clouds under this dome allows intense sunlight to further heat the ground and air.
How do jet streams and humidity contribute?
Heat domes are tied to shifts in the jet stream. When the jet stream bulges northward into a ridge, it locks warm air into place.
Kelsey explains that over the summer, this ridge can form in areas like the U.S. East Coast—often referred to as the “Bermuda High”—drawing humid air from the Gulf and intensifying heat stress.
Similar patterns occur near western landmasses, where moisture from the Pacific raises humidity levels.
Are they becoming more common?
Yes. Kelsey explains; heat domes are appearing “more frequently and more intensely,” thanks to a jet stream that has become more erratic in a warming world.
Events like the 2023 heatwaves in the southwestern U.S. were deemed “virtually impossible” without climate change, and 2025 has already seen deadly heat in Europe, China, and Australia.
How to stay safe during a heat dome
- Stay hydrated — your body needs water to cool itself.
- Avoid peak heat hours — limit physical activities in the afternoon.
- Access AC or cooling centers, especially in urban areas affected by the heat island effect.
- Be cautious with fans — they can help only when the air temperature is below roughly 99°F and humidity is high.
With extreme heat posing serious health threats, understanding heat domes is more than academic—it’s a matter of public safety.