A record-breaking heat wave is gripping much of the United States, shattering March temperature records across 14 states and showing no signs of abating. From the Southwest, where the intense heat first took hold, the dome of high pressure is expanding eastward, threatening to become one of the most widespread heat events in the nation’s history. The unusual warmth is raising concerns about early-season strain on infrastructure and potential health risks, even as spring is just beginning.
The National Weather Service (NWS) reports that the heat dome – a persistent high-pressure system that traps warm air – is expected to linger through at least the middle of next week. “Pretty much the entire United States is going to be experiencing some form of heat,” said meteorologist Gregg Gallina of the NWS Weather Prediction Center on March 23rd. “The area that’s seeing record temperatures is extremely large. It’s really unusual.”
Unprecedented March Temperatures
The scale of this heat wave is particularly striking. Jeff Masters, a meteorologist with Yale Climate Connections, explained that Flagstaff, Arizona, is poised to experience 11 to 12 consecutive days with temperatures exceeding the city’s previous March record. The heat is not limited to the desert Southwest. Gallina predicts temperatures in the Southern and Central Plains will reach around 30 degrees Celsius (86 degrees Fahrenheit), with many areas across the contiguous 48 states approaching or surpassing March temperature records.
According to Chris Burt, a weather historian and author of “Extreme Weather,” the current heat wave is projected to surpass two previous significant events: the 2012 heat wave in the Upper Midwest and Northeast, and the 2021 Pacific Northwest heat dome. The breadth of this event is what sets it apart.
A Relatively Dry Heat, For Now
While the temperatures are extreme, Gallina noted a mitigating factor: humidity levels are not as high as they typically are during summer heat waves. This lower humidity reduces the risk of dangerous heat index values, but still poses a threat, particularly to vulnerable populations. “That’s what’s been saving people a little bit during this heat wave,” he said.
On March 20th, four locations in Arizona and California reached a scorching 44.4 degrees Celsius (112 degrees Fahrenheit), according to the National Weather Service. This broke the U.S. Record for the hottest March day by 2 degrees Celsius and was just one degree shy of the warmest day ever recorded in April across the lower 48 states.
States Experiencing Record Warmth
Maximiliano Herrera, a climatologist and weather historian who tracks global weather records, has compiled a list of 14 states that have experienced their warmest March days on record since the onset of the heat dome: California, Arizona, Nevada, Kansas, New Mexico, Nebraska, Utah, South Dakota, Missouri, Iowa, Colorado, Wyoming, Minnesota, and Idaho. The National Centers for Environmental Information (NCEI) reported at least 479 stations broke March temperature records between March 18th and 21st. Herrera estimates the actual number is even higher, with 1,472 daily temperature records also falling during that period.
The Role of the Jet Stream and Climate Change
Experts point to a stalled jet stream – the high-altitude air current that steers weather systems – as a key contributor to the prolonged heat. The jet stream is currently blocked far to the west, allowing a high-pressure system to dominate over much of the country. This blocking pattern is also diverting storms, leading to torrential rains and flooding in Hawaii.
However, the underlying driver of this extreme weather is increasingly linked to climate change. A recent analysis by World Weather Attribution, an international group of climatologists, determined that the record heat wave was made more likely by human-caused climate change. The group found that the burning of coal, oil, and natural gas has increased the intensity of the heat wave by at least 2.6 degrees Celsius, according to Clair Barnes, a co-author of the report and researcher at Imperial College London.
Looking Ahead
Masters anticipates the heat dome will begin to weaken by the complete of next week. “We just need to hang in there a little bit longer,” he said. The NWS will continue to monitor the situation and provide updated forecasts as the heat wave evolves. Residents in affected areas are urged to stay hydrated, limit strenuous outdoor activity, and check on vulnerable neighbors.
Disclaimer: This article provides information about a weather event and should not be considered medical or emergency advice. If you are experiencing heat-related illness, seek immediate medical attention.
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