October pool days, hiking in shorts, and stand-up paddleboarding on Sloan’s Lake. Lately, the Mile High City’s fall has felt like, well, summer, so we understand if you’re skeptical when we say Denver’s first snow of the season might fall on Sunday. The first dusting is notoriously difficult to predict, and the Centennial State has been anything but consistent when it comes to winter weather.

On average, Denver typically sees its first snow on or around October 18. But that average date keeps getting pushed back thanks to the trend of warm autumns in recent decades. In 2021, Denver experienced its latest first snow on record, which came on December 10, 2021.

In Denver, temperatures have increased during the fall months (September, October, and November) by 2.8 degrees since 1970, according to Climate Central. This year, Denver is running 2.7 degrees above normal for monthly temperatures—which is why you may have been wearing your swimsuit this past weekend, instead of your snow boots. We’ve also had a mostly sunny fall season: The last rain in the Mile High City was on September 15.

Graphic courtesy of Climate Central

The culprit for this early fall warmth and dryness? A stubborn ridge of high pressure dominating the western United States. This ridge of high pressure has led to mild weather throughout the West, including at many ski areas. Other than a storm that dropped several inches of snow from Aspen to Steamboat on October 12, Mother Nature hasn’t been providing much powder so far this season.

But the forecast looks to be cooling just in time for Halloween. While we’ll stay warm and dry over the next few days, several disturbances could bring our first shot of widespread cold and some snow just before and on October 31. Whether or not this wintery weekend comes to fruition, it’s time to start looking out for strong cold fronts and widespread snow—especially with our friend El Niño in town.

During El Niño, the equatorial waters of the Pacific Ocean are warmer than usual, which can lead to blustery winter conditions. In general, Colorado experiences snowier-than-normal winters, especially across the southern portion of the state, during El Niño years. Looking at past El Niño cycles, we can expect temperatures through February to be near normal.

But as the jet stream—that river of moving air above us—drags across the southern United States, the Centennial State could see some major upslope snowstorms throughout the winter. Upslope snowstorms occur when a ridge of low pressure moves across southern Colorado or northern New Mexico. The ridge’s counterclockwise winds pull warm, wet air from the Gulf of Mexico, and then dump copious amounts of snow on the Front Range. Put another way, there may be some epic powder days ahead.

So soak in these last few days of sunny and 75-degree weather—and make sure those skis are waxed and the edges are nice and sharp, because it won’t be long before cold temps and snow replace the sunshine.

Andy Stein
Andy Stein
Andy Stein is a freelance meteorologist with experience working on both local and national television.