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By Anna Skinner
Associate News Editor
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One meteorologist issued a warning that winter isn't over just yet as evidence points toward a rising possibility of a major sudden stratospheric warming event later this month that will possibly plunge temperatures back to frigid levels.
Forecasters are monitoring a rare atmospheric event known as sudden stratospheric warming (SSW), which could significantly disrupt the polar vortex later this month. Such events can shift weather patterns across the country by destabilizing the polar vortex high above the North Pole, potentially allowing frigid Arctic air to surge into North America. A similar event struck the U.S. late last year. When such an event occurs, it can lead to a surge of cold temperatures across the mid-latitudes, including the U.S.
"A major warmup is coming to the East, but winter isn't over," The Washington Post meteorologist Ben Noll posted on X. "The second major sudden stratospheric warming event of the season means that Old Man Winter still has a few tricks up his sleeve in mid-to-late March. Don't put away the shovel just yet!"
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After several weeks of temperatures forecasted to be above normal in the lower atmosphere, a surge of well-below average temperatures will hit the U.S. in mid-March, according to a map included with Noll's post.
When reached for comment, a National Weather Service spokesperson referred Newsweek to the NWS Climate Prediction Center's (CPC) outlooks, which discuss the SSW.
"A sudden stratospheric warming (SSW) event is ongoing, and dynamical model forecasts depict a weakening of the stratospheric polar vortex during March," the outlook said. "These events sometimes extend into the troposphere, and can result in a robust negative phase of the Arctic Oscillation (AO), allowing cold, arctic airmasses to invade the mid-latitudes. Dynamical model guidance maintains a fairly robust positive AO-type structure during the Weeks 3-4 period, however. Therefore, the influence of the stratospheric polar vortex on the outlook is highly uncertain, as these events do not always extend robustly into the troposphere."
In the monthly outlook, the NWS CPC said the SSW is expected to be short-lived.
What Is a Major, Sudden Stratospheric Warming Event?
Major SSW events occur when temperatures high above the Arctic rise abruptly, weakening or even splitting the polar vortex and allowing frigid air to spill southward into the mid‑latitudes. Although the precise U.S. impacts depend on how the stratospheric changes couple with lower‑atmosphere patterns, past events of this magnitude have triggered widespread cold outbreaks and increased snow potential across large portions of the country.
Sudden stratospheric warming events can raise stratospheric temperatures by as much as 70 degrees Fahrenheit in just a few days. This rapid warming disrupts normal wind patterns, ultimately weakening the polar vortex and allowing the jet stream to move more erratically. As a result, cold Arctic air may spill into lower latitudes, bringing abrupt and severe cold waves.
U.S. Temperature Outlook
As of Monday, current temperature outlooks from the NWS CPC remain above average for nearly the entire country. The NWS Weather Prediction Center recently shared a timelapse of high temperatures across the U.S. this week, which will surge to 25 degrees or higher above average in some locations across the Midwest and Northern Plains. Simultaneously, temperatures in the Southwest and in Texas could even reach the low 90s.
Looking even further ahead, the NWS CPC anticipates above-average temperatures to persist across much of the country for the foreseeable future, according to three- and four-week temperature outlooks.
"Warm temperatures will be the theme of the week for most of the [continental US]," NWS said in a Monday forecast. "Amplified ridging will set-up across the central and eastern U.S. and effectively push a warm front through the Arctic high present across the Great Lakes. Daily high temperatures will be in the low to middle 80s across much of the South this week."
It added: "By Tuesday and Wednesday, high temperatures in the middle to upper 70s will be possible farther north into the Ohio and Tennessee Valleys as that front lifts out of the region. The West will cool off as an upper trough and surface cold push through the region, but temperatures are still expected to be slightly above average."
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