Meteorologists are calling for superlatives, saying the arrival of a heat wave so intense and rare for this time of year that some areas could break April temperature records before the month even begins.
This extreme event, made worse by human-induced climate change, brings summer-like temperatures during March from California to Texas and as far north as Montana. Heat warnings and other heat warnings have been issued for millions of people from San Francisco to Phoenix and are likely to expand over time.
The event has just begun. By the end of next week, the weather will scorch much of the western part of the country and parts of the Plains states, upending dozens of daily and monthly temperature records by unusually wide margins.
For example, in Phoenix, the all-time record high temperature in March is 100 degrees, and during this heatwave, temperatures are expected to rise to at least 106 degrees and remain above century levels for several days.
“Many regions are likely to record both the highest temperature for March and the earliest 100 degrees on record,” the National Weather Service said, predicting high temperatures for this time of year to be up to 30 degrees above average.
The extreme heat could rival the 2021 Pacific Northwest heatwave in June, which killed hundreds of people and soared into the 120s Fahrenheit in Oregon and Washington states. Temperatures over the next two weeks won’t be that hot (it’s still March, after all). However, both events originated from the same place. That means a dome of record heat has been stationed in certain parts of the country for an extended period of time, along with a healthy dose of climate change.
Heat domes are vast, powerful areas of high pressure that extend thousands of feet into the atmosphere. That pressure pushes down on the air beneath it, compressing it and heating it. This also suppresses storm activity, with the thermal dome acting like a diversion beacon in the atmosphere, changing the route of the storm. This dome is likely to set a record for annual strength and could match or even surpass previous heatwave domes that have existed during the summer, such as the 2021 event.
Its intensity is important because meteorologists use such measurements in addition to surface temperatures to compare heat waves throughout history and study the effects of climate change.
Research shows that the 2021 heat wave would have been virtually impossible without climate change caused by fossil fuel burning. Studies have repeatedly shown that as the Earth warms, heat waves become more likely to occur, last longer, and become more severe. Since that initial heat wave event, we know that multiple heat waves in other parts of the world are only possible due to human contributions from global warming pollution.
Meteorologist and Colorado State Climatologist Russ Schumacher said the strength of the heat dome in March was “astounding.” Other meteorologists took to social media to describe the heat dome’s strength as “truly amazing” and “mind-boggling”.
“As the world warms, we expect warm conditions to become more likely and occur more frequently,” Schumacher said. “When we have a heat wave, we expect it to be warmer or last longer.”
“But it just takes a really unusual weather pattern for something like this to happen, and we’re going to see similar conditions this week,” he said.
Heatwaves also pose a serious threat to public health.
Extreme heat is typically the No. 1 cause of weather-related deaths in the United States each year, and early-season heat waves pose an especially serious public health risk because residents in the West are not yet accustomed to temperatures in the high 80s to low 100s, depending on location. The threat is further exacerbated by the lack of air conditioning in some of the affected areas.
The health threat is also multifaceted. During the summer, people can escape to rivers and lakes to soothe their spirits, but it’s still March, and hypothermia is a serious risk for anyone trying to get into the water to cool off.
The initial heat could linger for months and could have other deadly effects, including causing the region’s already low snowpack to melt at least a month earlier than planned. This raises water supply concerns and wildfire concerns for the upcoming dry season.
The West entered this heatwave on the heels of the hottest winter on record. Schumacher said Colorado’s snowpack was the thinnest since 1981. “March is the time of year when there are usually many snowstorms, and snowpack continues to accumulate on the mountains,” he says. “And this week it looks like we’re going in the exact opposite direction.”
In California’s Sierra Nevada Mountains, where snowfall has been near normal this winter, the remaining snowpack from the heat wave will quickly disappear, about five weeks earlier than normal, and perhaps completely.
Schumacher said that to better predict what’s to come in the West, it’s important not only to study heat waves but also to understand why this winter has been so warm in the West. “Future warming will probably make warmer months and seasons like this more likely,” he says.
