What is a heat dome? The climate phenomenon behind record heat

Here’s what causes heat domes, how climate change may be fueling them, and what you can do to protect yourself from extreme heat.   

What is a heat dome?

A heat dome is a meteorological phenomenon produced when a large area of high pressure in the atmosphere forms a ridge over a region and stays there for days or even weeks.   

“This ‘dome’ acts like a lid, preventing heat from escaping and blocking cloud formation, which leads to persistently high temperatures and minimal relief from the heat,” explains AccuWeather Meteorologist Brandon Buckingham.

When hot air attempts to rise it’s blocked by the high-pressure ridge. As it sinks, it compresses and grows steadily hotter, producing conditions of extreme heat near the surface over areas hundreds of miles in size.  

These oppressive heat events are nothing new. However, the term “heat dome,” which isn’t a formal scientific term, has become a popular way to describe the phenomenon in recent years.