US suffers hottest March day ever recorded as heat dome drives up temp

20 March، 2026

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Preliminary readings of sites in Arizona and southern California indicate that the US has suffered its hottest March day on record.

Large parts of the southwest of the United States are trapped in a dangerous heatwave, made worse in some places by a heat dome, with temperatures reaching around 43C (110F) at testing sites.

The heatwave has shattered March temperature records all over the southwest of the country, with hot weather arriving months ahead of schedule.

“This is what climate change looks like in real time: extremes pushing beyond the bounds we once thought possible,” said University of Victoria climate scientist Andrew Weaver.

March’s heat would have been virtually impossible without human-caused climate change, according to a report released today by World Weather Attribution, an international group of scientists who study the causes of extreme weather events.

What is a heat dome?

A heat dome is loosely defined as an area of high pressure that stays over the same area for days, or even weeks.

Hot air is trapped underneath like a lid on a saucepan, pushing temperatures above what’s normal for the time of year.

The heated air expands upwards into the atmosphere, then high pressure from above acts as a lid, meaning it can’t escape and causes the air to subside or sink – creating a dome effect.

As the warm air sinks, it compresses and heats up, which then traps more heat underneath and clouds are pushed around it, keeping the heat in even more.

The area of the US being hit by extreme weather in the past five years has doubled compared with 20 years ago, according to the National Oceanic and Atmospheric Administration’s Climate Extremes Index.

The extreme conditions are expected to persist and expand east in…

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