Europe is sizzling under an early heat wave this week, with millions of people experiencing extremely high temperatures, and experts say a phenomenon known as a heat dome is to blame.Here’s what to know.Heat domes are essentially high pressure systems that remain stationary for a few days, trapping dangerous heat and humidity, said Mireia Ginesta, a research associate at the Climate Litigation Lab at the Smith School of Enterprise and the Environment.Heat domes result from a northward bulge in the jet stream — a river of fast-moving wind at high elevations — that create the weather we experience. “High pressure system means that the air is sinking, and as the air goes down to lower altitudes, it becomes compressed,” Ginesta said. “So the pressure increases and the temperature also increases.”How does a heat dome play a role in heat waves?
People cool off at a fountain in Rome, Tuesday, June 23, 2026. (AP Photo/Alessandra Tarantino)
Those “bulges” are what set up the conditions that lead to a heat wave, said Jennifer Francis, a climate scientist at the Woodwell Climate Research Center.“The heat dome is really what the jet stream is doing,” Francis said. “The heat wave is what we feel at the surface.”
