This weird winter was one of the warmest — and coldest — on record. It’s a glimpse of our future

This Weird Winter Was One of the Warmest — and Coldest — on Record. It’s a Glimpse of Our Future

The Lower 48 states experienced a stark divide this winter, with the East grappling with freezing temperatures and the West basking in unusually mild conditions. While residents in the eastern region endured harsh cold, snow, and ice for weeks, those in the western states found themselves in a starkly different climate. The outcome revealed the West’s temperatures as the dominant factor, with this season likely to be classified among the region’s warmest. Two preliminary datasets indicate that the contiguous U.S. faced its second-warmest winter on record, underscoring the profound shifts in weather patterns.

A Tale of Two Extremes

Despite the East’s severe cold, few locations there set record-breaking lows. In contrast, numerous western cities recorded their hottest winter in history. For instance, Salt Lake City, Phoenix, Las Vegas, and Cheyenne, Wyo., all saw unprecedented warmth. Even Denver, known for its mountainous climate, experienced more 60-degree days than Myrtle Beach, South Carolina, during the winter months. This contrast highlights how climate change is reshaping seasonal extremes, where once-reliable cold snaps no longer dominate.

“The dice are loaded,” Martin said. “As the world warms, it’s clear that cold pools are likely to keep shrinking and winters of the future are more likely to keep breaking warmth records.”

Climate scientists have observed that winters used to be colder than today, with the western U.S. now warming faster than other seasons. This trend is supported by data on the Northern Hemisphere’s “cold pool,” a layer of air around 5,000 feet where snow forms. Jonathan Martin, a meteorologist at the University of Wisconsin-Madison, tracked the cold pool’s size since the 1940s. His analysis showed this past winter had the smallest cold pool in the entire dataset, aligning with a long-term contraction in its reach.

Although the cold pool was smaller, its presence over heavily populated eastern areas created the perception of an unusually cold season. Martin notes that the cold pool’s location near Hudson Bay, Canada, and its frequent disruptions by Arctic air outbreaks contribute to this effect. He describes the cold pool as a unique indicator of human-driven climate change, offering the first conclusive evidence of winter warming in the hemisphere’s free atmosphere.