The West is Boiling: Record Warmth in Winter
The winter of 2025-2026 has officially gone down in history as the hottest on record for much of the western half of the United States. But here's where it gets controversial: while the East was cooler, it wasn't enough to prevent the country from having its second-warmest winter overall. So, what's going on out West? Let's dive in.
A large swath of the western half of the country, from Southern California to the High Plains and Northern Rockies, had its warmest meteorological winter (December through February) on record, based on 131 years of climate data. Phoenix, Arizona, shattered its previous record by almost 3 degrees, a record that was only a year old. Albuquerque, New Mexico, broke its previous record by 3 degrees, according to the Southeast Regional Climate Center. Helena, Montana, Las Vegas, and Lubbock, Texas, were among the other cities that were record warm this winter.
But it's not just about temperatures. The Midwestern Regional Climate Center developed the Accumulated Winter Season Severity Index (AWSSI) as a measure of how impactful winter has been based on both temperature and snowfall. And monitoring sites across the western half of the country are experiencing record mild winter seasons. It's worth noting that the AWSSI isn't limited to meteorological or astronomical winter, but rather the period of time with weather that meets certain meteorological criteria. So, 'winter' can still be ongoing for some sites, even as March begins.
So, what happened? A ridge of high pressure dominated the western half of the country, allowing for consistent warmer weather to prevail. This trend is associated with the negative phase of the Arctic Oscillation (AO), a global circulation pattern in our atmosphere that indicates the strength of the polar vortex. When the AO is in a negative phase, the polar vortex is weaker, which allows for colder air to spill into the eastern half of the country while trapping the western half under warmer conditions.
Now, you might be wondering: what does this mean for the future? Well, that's a thought-provoking question. While warmer winters might seem like a good thing, the lack of snow can have a ripple effect as we move into warmer months due to a diminished snowpack. So, while the West is boiling right now, it's important to consider the long-term implications of these record-breaking temperatures. What do you think? Do you agree or disagree with this interpretation? Let us know in the comments!
