4 min readNew DelhiJul 6, 2026 11:14 AM IST
First published on: Jul 5, 2026 at 06:49 PM IST
After record temperatures were reported in recent weeks across India and Europe, the United States is now witnessing a prolonged heatwave.
The US National Oceanic and Atmospheric Administration (NOAA) stated that a persistent “heat dome” will bake a good chunk of the US on the Fourth of July weekend, with high temperatures soaring 10-20 degrees F above average. Numerous daily temperature records are expected to be surpassed.
Seen as part of a trend over the last few years, this is not entirely unusual. The year 2023 saw a severe heat wave event over the southwestern US and Mexico, lasting from mid-June to early August and affecting over 100 million people. Year-on-year, the effects of man-made climate change are also intensifying natural phenomena such as El Niño, and scientists have identified it as a key reason for the ongoing European heatwave.
This year, and in 2023, one of the drivers of the heatwave was a heat dome. Here is what to know about it.
What is a heat dome?
A heat dome is a weather phenomenon in which a high-pressure system in the atmosphere traps warm air for an extended period.
As NASA puts it, heat domes put the brakes on the process of convection, in which relative temperature differences drive the movement of air. As a result, clouds and precipitation are also suppressed. Sunlight reaches the Earth’s surface relatively unhindered and further elevates air temperatures.
In Europe, too, an “Omega Block”, which is a kind of heat dome, is also contributing to the higher-than-usual temperatures this year. Generally, high-speed winds known as jet streams blow from the west to east over Europe, moving weather systems, but this has been disrupted.
Writing for The Conversation, meteorologist William Gallus explained that the “stagnant” weather pattern that allows a heat dome to exist usually results in weak winds and an increase in humidity. “Both factors make the heat feel worse – and become more dangerous – because the human body is not cooled as much by sweating,” he wrote. High humidity also reduces the amount of cooling at night that is necessary for recovery.
How is climate change impacting heat domes?
Scientists are still debating how climate change is impacting the blocking weather events that cause heat domes. However, they have ascertained that rising global temperatures have made heat domes larger and more intense.
A 2021 study carried out by an international team of 27 climate researchers, who were part of a collective known as World Weather Attribution, found that searing temperatures during the heat dome in Canada that year would have been “virtually impossible” without climate change.
What is beyond doubt is the increasing frequency of heat waves in the United States. A NASA modelling system that analysed long-term trends found that summer heat waves in the US roughly doubled in number between 1980 and 2023, increasing from an average of two to four per month.
“For many years, climate scientists working with the Intergovernmental Panel on Climate Change (IPCC) and NASA have pointed out that the frequency and intensity of heatwaves have increased in recent decades because of the rising concentrations of greenhouse gases in the atmosphere. They expect these increases to continue in the future,” NASA said.
People cool off at Grand Haven State Park along Lake Michigan on June 30. (Joel Bissell/Kalamazoo Gazette via AP) 
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