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A large heat dome is spreading across the United States and breaking March heat records.
Weather historians say the dome has already broken state records for March in 14 states.
Now, the intense heat baked in the Southwest is creeping eastward and could end up being one of the longest heat waves in American history, meteorologists and climate historians say.
Experts say the location of the heat wave could compete with major events in 2012 and 2021.
And it won’t end for a while, possibly until the middle of next week as April begins, said meteorologist Gregg Gallina of the National Weather Service’s Weather Prediction Center.
“Basically the whole US is going to burn,” Gallina said Monday. “The area of record temperatures is very large. That’s the strangest thing.”
This heat wave — where high pressure acts like a lid to trap hot air in an area — will leave Flagstaff, Ariz., with 11 or 12 straight days of higher temperatures than the city’s previous March record, said meteorologist Jeff Masters of Yale Climate Connections.
Dave Phillips, Environment Canada’s senior meteorologist, explains what conditions are creating the heatwave and how the ‘oppressive and extreme’ temperatures are locked in for days.
Gallina said the eastward movement of the dome will mean temperatures in the mid-30s C (90s F) Wednesday in the southern and central Plains. From one-quarter to one-third of the 48 states will be flirting with records in March, Gallina said.
How does it compare to other record breakers
The physical location of this heat wave is likely to exceed other heat waves in history – one in 2012 in the Upper Midwest and Northeast and another in 2021 in the Pacific Northwest – according to climate historian Chris Burt, author of the book. Extreme Weather.
It may not be as big as the 1936 Dust Bowl heat wave, but that was a series of heat waves over a two-month summer, not a major event right now, Burt said.
Both the Dust Bowl and the 2021 heat wave were intense, with high temperatures that hurt people the most because they fell in June and July, Gallina said.
Another saving grace for people in this heat wave is that it’s not as humid as it would be if temperatures rise in the summer, Gallina said.
How hot is it? And where?
On Friday, four locations in Arizona and California hit 44.4 C (112 F), according to the weather service.
Not only did that break the record for the hottest March day in the continental United States by 2 C (4 F), but it was just 1 F shy of the hottest day recorded in the Lower 48 in April.
Meteorologist and climate historian Maximiliano Herrera, who tracks weather records around the world, compiled a list of 14 states that have not yet seen their hottest March day on record since the heat zone began: California, Arizona, Nevada, Kansas, New Mexico, Nebraska, Utah, South Dakota, Missouri, Iowa, Colorado, Wyoming, Minnesota and Idaho.
“In Mexico, even the May records were abandoned by the March records that were broken up to 14 (degrees Fahrenheit), more than July 1936, March 1907 or June 2021,” Herrera wrote in an email.
The National Center for Environmental Information registered at least 479 record-breaking weather stations in March from Wednesday to Saturday, based on the network of stations.
Herrera, who analyzed a wider set of data, said the true number is likely higher. Another 1,472 records – which are easy to break – were broken at the same time, the center said.
What causes dome heat
What happens is the jet stream — which moves weather systems from west to east — gets stuck more westward as storms move up Hawaii, where people see rain and flooding, Masters and Gallina said.
The storm brought more than 100 centimeters of rain to Hawaii, causing the worst flooding in 20 years. The floods forced thousands from their homes, and the National Guard was brought in to help evacuate people from the floodwaters.
On Friday, an international group of climate scientists called the World Weather Attribution determined that record heat is “almost impossible” and 800 times more likely to occur due to climate change caused by the burning of coal, oil and natural gas. The result of those activities added at least 4.7 F (2.6 C) to the temperature, said co-author of the report Claire Barnes, a scientist at Imperial College London with the group.
The report warned that the hot dome is expected to cause the snow to melt faster and faster in the mountain areas of Colorado and California. This can reduce the amount of water available in the summer, leading to an increased risk of wildfires and the risk of water shortages.
The heat dome will continue into late next week, Masters said. “We have to take our time.”
