Why is this winter so cold?
While the eastern US is experiencing severe winter, the western region of the country has seen record heat.
People walk on a street in Brooklyn, NY on February 7, 2026, the day an “extreme cold warning” was in effect.
Spencer Platt/Getty Images
The latest bout of brutal cold weather has plagued the eastern US for weeks, bringing wind chills into the negative teens and 20s Fahrenheit (negative mid 20s to low 30s Celsius) across the US Northeast over the weekend. Meanwhile, in the West, winter has brought record-breaking heat that is more suitable for spring and even summer. “I’m sitting in a T-shirt at a mile high here in Colorado in early February,” says climate scientist Daniel Swain. California Institute for Water Resources.
This huge disparity is the result of persistent atmospheric patterns. However, this pattern is about to break and the weather fortunes are about to change in both parts of the country.
To explain what’s going on, let’s review a favorite winter weather bugaboo: the polar vortex. The whirlpool is like a circular flowing river of wind that carries with it the bitterest cold air in the Arctic. When the vortex weakens, that tight circle undulates, Swain says, like a slow-flowing river meandering across the landscape.
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Where the vortex bends towards the south, cold air comes. And if it bends south at one place, it must bend north in adjacent areas. In this case, the northward tilt is occurring over the western US, where it has drawn warm air.
Swain says those turns are set up in ways that reinforce background conditions related to Earth’s geography. In the case of the US, the location of the Rockies, as well as the boundary between the Pacific Ocean and land, means that, on average, a weak ridge (a northward turn in the jet stream) forms in the west and a weak trough (a southward turn) establishes in the east. The current conflict, says Swain, “is an amplification of that background pattern – a dramatization.”
The rapid warming of the Arctic is making this kind of weakening of the polar vortex more common, but researchers aren’t sure yet. “To the extent that it’s doing that, it’s not enough to overcome the fact that that source of bitter cold air is not as bitterly cold as it used to be,” Swain says.
This affects the current situation. In the period from December 2025 to January 2026, there were no record cold events in any part of the contiguous United States. But in 21 percent of the country it was the hottest period since 1940. climatologist brian bretschneider.
And as winters get warmer overall, these bouts of extreme cold become more disruptive because they are so uncommon. People are not accustomed to cold weather, and businesses cannot make contingency plans. “For someone who is 25 or 30, this may have been the coldest week of their life,” Swain says, while, for people outside the West, “this has been the warmest winter we’ve had, regardless of age.”
Although the consequences of the cold have been widespread and intense – with travel disruptions, power outages and many deaths – the warmer western winter will also take a toll. Although the consequences will be delayed, the risk of drought, water shortages and wildfires may increase in the coming months.
The upcoming climate change will likely be caused by subtle atmospheric changes. Swain says understanding the details will require a dedicated study to uncover all the impacts, but it could lead to changes in how hurricanes form in the tropical Pacific, which could destroy things in the atmosphere like dominoes. Whatever the cause, temperatures will rise to more seasonal levels in the eastern US, and cooler, wetter weather will arrive in the West. Any rain or snow would be welcomed, Swain says, but unlikely to eliminate existing losses.
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