Denver, a city often associated with brisk winter days and the occasional white Christmas, found itself in the grip of an extraordinary heatwave on December 22, 2025. As the sun climbed higher in the sky, so did the mercury, shattering long-standing records and leaving residents and meteorologists alike shaking their heads in disbelief. According to 9NEWS, by 1:20 p.m. at Denver International Airport, the temperature soared to a staggering 76 degrees—making it not only the hottest December 22 in 86 years, but also the second-warmest December day ever recorded in the city. The only day to surpass this was December 5, 1939, when Denver reached an almost surreal 79 degrees.
The average high for this time of year? Just 43 degrees. For comparison, 76 degrees is what Denverites typically expect on May 27, not when they’re stringing up holiday lights and prepping for Christmas dinner. Meteorologist Chris Bianchi from the 9NEWS Weather Impact Team captured the city’s collective astonishment, remarking, “What we’re seeing today, really, really unusual for this time of year. We have 60 degree days in December, that’s common. Seventy and especially 75 degrees, that’s really out of whack.”
It wasn’t just Denver feeling the unseasonable warmth. Across the metro area, records tumbled. As Colorado Public Radio (CPR) reported, Boulder Municipal Airport registered 72 degrees by 10:52 a.m., while Vance Brand Airport in Longmont hit 71 degrees around the same time. The National Weather Service (NWS) in Boulder had forecast a high of 73 degrees for the day, and their predictions were right on the money. The previous December 22 record high of 70 degrees, set back in 1955, fell by the wayside as the day progressed.
So what was behind this remarkable warmth? NWS Meteorologist Bruno Rodriguez explained to CPR, “We’ve got some west winds kind of downsloping off of the mountains. Whenever we have that, we tend to have warmer temperatures as well, as that warm air comes down the mountain and compresses. So both of those things are helping to push temperatures well above average.”
But this warmth came with a price. The Front Range, from the Boulder County foothills south into South Park and the Palmer Divide, was under a Red Flag Warning until 5 p.m. Monday. The culprit? A potent combination of gusty winds—peaking at 60 mph in the foothills and 30 to 40 mph west of I-25—and bone-dry air. Rodriguez noted, “The temperatures and humidity often go hand in hand, and we’re seeing that today. So, it’s just as dry as it is warm, looking at humidity, dropping down into the low teens across the base of the foothills in areas west of I-25. So combined with those gusty winds, that’s what’s resulted in another critical fire weather day for those areas.”
Indeed, the region’s relative humidity plummeted, creating the perfect conditions for wildfires to ignite and spread rapidly. Local officials and meteorologists urged residents to exercise caution, especially with outdoor activities that could spark a blaze. The Red Flag Warning underscored just how quickly a pleasant December day could turn dangerous under the wrong circumstances.
As the afternoon wore on, winds were expected to subside somewhat, but the warmth persisted. Overnight, the metro area was forecast to stay well above freezing, with temperatures in the mid- to upper-30s, while the foothills would linger in the 40s, still breezy. Even as the sun set, the city’s heatwave showed little sign of abating.
Looking ahead, the forecast painted a picture more reminiscent of spring than winter. According to 9NEWS, Denver’s weather was set to remain mostly sunny and mild, with highs between 43 and 71 degrees through Sunday, December 28. Christmas Eve and Christmas Day were both expected to be unseasonably warm—highs of 67 degrees and a possible 71 degrees, respectively. If the Christmas Day high reaches 71 degrees, it will topple the previous record of 69 degrees set in 2005. Bianchi told viewers, “If you’re looking for when it will actually feel a bit more December-like, it’ll be this upcoming weekend.”
Rodriguez from the NWS added, “We could see some slight warming on Christmas Day itself. So, we’re looking at high temperatures across the urban corridor, generally in the mid- to upper 60s every day, including for Christmas Day. It’s not even out of the question. We might scrape 70 degrees potentially on Christmas.” For many, the prospect of a balmy Christmas is both a novelty and a concern.
While some residents reveled in the chance to stroll outside in short sleeves, others worried about the broader implications. The combination of warmth, wind, and low humidity has become all too familiar in recent years, raising questions about the region’s vulnerability to wildfires and the changing climate patterns that seem to be fueling such extremes.
Historically, Denver’s December temperatures have fluctuated, but the city has rarely seen such an extended spell of warmth this late in the year. The previous record highs, set decades ago, are now being matched or surpassed with increasing frequency. And with the Red Flag Warning in effect, the risks associated with these new weather patterns are impossible to ignore.
For now, the city is bracing for a holiday season unlike any in recent memory. The forecast—mostly sunny skies, mild days, and only a brief return to cooler weather by the weekend—means that holiday traditions may look a little different this year. Snowmen are out; perhaps a game of touch football in the park is in.
As Denver and its surrounding communities adjust to this unprecedented December warmth, meteorologists and residents alike are left to wonder: Is this just a fluke, or a sign of things to come? With temperatures smashing records and Red Flag Warnings becoming a regular feature of the winter landscape, the Mile High City is getting a firsthand look at the unpredictable face of modern weather.
Whatever the future holds, one thing is certain: December 22, 2025, will go down in Denver’s history books as a day when the city’s winter was turned upside down—and when the only thing more surprising than the temperature was how quickly it rewrote the record books.
