The West is Boiling: Record Warmth in Winter
Winter 2025-26: A Record-Breaking Heatwave in the West
The winter of 2025-26 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 remained cooler, preventing the country from experiencing its record warmest winter overall, the West was on fire! This is the part most people miss: a large swath of the western half, from Southern California to the High Plains and Northern Rockies, had its warmest meteorological winter on record, based on 131 years of climate data.
Record-Breaking Temperatures Across the West
Several cities can now claim winter 2025-26 as their warmest on record, including Salt Lake City (152 years of data), Tucson (130 years of data), and Rapid City, South Dakota (114 years of data). Phoenix, Arizona, obliterated its previous record by almost 3 degrees, a pummeling of a record in the realm of three-month temperature data. Albuquerque, New Mexico, clobbered its previous record warmest winter by 3 degrees, according to the Southeast Regional Climate Center. Helena, Montana, Las Vegas, and Lubbock, Texas, were among the other cities record warm this winter.
It's Not Just Temperatures: The AWSSI
When it comes to winter, temperatures are just part of the story when it comes to determining how mild it has been. 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. 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.
What Happened: The High Pressure Ridge
A ridge of high pressure has 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. This is a major clue to why the West was so warm.
The Ripple Effect of Snowpack
All of this to say, many locations across the West have not only dealt with warm temperatures this winter. They also had to contend with a lack of snow that can have a ripple effect as we move into warmer months due to a diminished snowpack. This is a thought-provoking question for our audience: what will be the impact of this record warmth and lack of snow on the West in the coming months and years?
Comment Hooks: Join the Discussion!
Do you agree or disagree with the interpretation of this record warmth in the West? Share your thoughts in the comments below! Remember, every opinion matters, and we want to hear from you.
