Bold take: the West didn’t just have a milder winter — it shattered long-standing records and reshaped how we understand seasonal norms. Here’s a clear, beginner-friendly rewrite that preserves every key detail while adding context and some helpful explanations.
But here’s where it gets controversial: the wider impact of a record-warm winter goes beyond temperatures and touches on snow, water resources, and local economies. Let’s walk through what happened, why it happened, and what it could mean for you.
Record warmth dominates the West
- Meteorological winter (December through February) 2025-2026 ended with the Western half of the United States experiencing its warmest winter on record, based on 131 years of climate data. This stretches from Southern California up through the High Plains and Northern Rockies.
- In contrast, the eastern half of the country stayed cooler, which kept the overall contiguous United States from achieving its warmest winter ever. As a result, the U.S. as a whole logged its second-warmest meteorological winter on record.
- Several cities with lengthy data records noted their warmest winters yet, including Salt Lake City (152 years of data), Tucson (130 years), and Rapid City, South Dakota (114 years).
- Phoenix, Arizona, shattered its previous winter record by nearly 3 degrees, a substantial leap given that its prior record had only been set a year earlier. Albuquerque, New Mexico, also surpassed its previous warmest winter by about 3 degrees. Helena, Montana; Las Vegas; and Lubbock, Texas, were among other cities recording their warmest winters.
Temperature isn’t the whole story
- While daytime highs grabbed headlines, winter severity isn’t defined by temperatures alone. Researchers use the Accumulated Winter Season Severity Index (AWSSI) to capture the combined effects of temperature and snowfall. Western sites tracked by AWSSI show record-mild winters, indicating overall milder winter experiences beyond just warm days.
- It’s important to note AWSSI isn’t limited to meteorological or astronomical winter. It tracks periods that meet particular weather criteria, which means some locations may still consider winter ongoing even as March begins.
- The warmth isn’t just about comfort: a lack of snow carry-through can ripple into spring and summer, as reduced snowpack can affect water resources and downstream ecosystems.
What drove the warmth in the West
- A persistent ridge of high pressure dominated much of the western U.S., promoting sustained warmth and steering storm tracks farther north. This limited snowfall in the mountain ranges that usually crown winter with snowy conditions.
- The broader climate signal aligns with the negative phase of the Arctic Oscillation (AO). In a negative AO, the polar vortex weakens, allowing colder air to spill into the eastern half of the U.S. while the western half remains unusually warm.
Bottom line and questions for discussion
- The West’s record-warm winter came from a combination of unusual jet-stream behavior and larger atmospheric circulation patterns, amplifying warmth and limiting snow. For the whole country, the contrast between a warm West and cooler East helped keep the national winter from breaking the all-time warm record.
- This situation underscores how regional winters can diverge dramatically due to shifting circulation patterns, and why AWSSI provides a more holistic view of winter impacts than temperature alone.
Discussion prompts: Do you think regional warming patterns will persist, or could we see a rapid shift back toward colder winters in the near term? How should communities adapt to increasingly variable winter conditions, particularly in terms of water resources and snow-dependent activities? Share your thoughts below.
