Rain on Christmas Day. It fits in with a broad pattern

Maybe rain on Christmas day wasn’t a result of climate change, but 2024 continued to warm across Colorado

by Allen Best

It rained on Christmas in metro Denver— nearly an inch in western Arvada, snuggled against the foothills. Is this a climate change story?

It hasn’t happened since before I was born, but it has happened. Chris Bianchi, a meteorologist on Channel 9, told viewers the next night that Christmas rain in Denver had been recorded in 1892, 1922 and 1942.

“If hard to say definitively, most likely that’s not the influence of climate change,” he said. Conversely, he added, having snow days doesn’t mean that climate change is not occurring.

What is strong evidence for climate change, he said, were the temperatures in December through Christmas Day, an average 40 degrees, about 9 degrees above the long-term average. “That probably has something to do with climate change,” he said.

A few days remain in 2024, but it looks to be an extremely warm year for the record books.

On Dec. 22, Russ Schumacher, the state climatologist, posted at the Colorado Climate Center that the December warmth provided a “bookend to what will end up as one of the warmest years on record statewide.”

He also posed a map for Dec. 15-21 of temperature data courtesy of NOAA.

“Typically when we see maps like these, we get suspicious about problems with the data or a faulty thermometer, but this isn’t an error. Gunnison has truly been an anomaly in the state’s weather and climate this month.”

Gunnison’s temperatures had been 13 degrees colder than average in the first three weeks of December, and while people in Denver were wearing shorts, in Gunnison the high was 26 degrees. Gunnison had actually had record lows on Nov. 30 and Dec. 1.

The anomaly, Schumacher explained, was likely due to the geography of the Gunnison Basin, a high mountain valley where cool air tends to pool, especially when there is a strong snow cover. Why the same would not apply to Middle or North Parks, two other high-mountain valleys known for their cold weather, he did not say.