Why Do the Mountains Get So Much Snow in January but Denver Doesn’t?

To some, January is synonymous with cold and snow. But in Denver, only one of those things is really true. In fact, while January is the city’s coldest month of the year (average temp of 30.7 Fahrenheit), it consistently features less snowfall than December, February, March, and April. While it might seem natural that cold air would bring higher snow totals, that’s not always the case.

Here are a few reasons why Denver doesn’t typically get hammered with the white stuff in January:

Downslope Winds
Denver is positioned almost perfectly at the base of the Rocky Mountains, and therefore it normally sees winds that come down from the Continental Divide. Winds that blow down a mountain side are called downsloping winds, which cause warming temperatures, drying conditions, increased stability, and clearing when clouds are present. Cue one of the reasons why Denver is so sunny throughout the winter months and sometimes very warm. The jet stream—a narrow band of very strong winds several miles up in the atmosphere—carries storms and moisture from far distances (think the Pacific Ocean). Since the jet stream brings winds from the west to the east, we typically see winds coming down from the mountains.

Cold Temperatures
Denver sees some pretty cold temperatures throughout the year, but January is the coldest on average. Contrary to what you might think, cold air does not hold moisture as well as warm air, so the month is typically drier—hence the need for so much Chapstick and lotion during the winter. Also, January sits right in the middle of the winter months, so temperatures have had time to normalize slightly, meaning there’s less of a temperature gradient across the region, something that normally fuels storms. The lack of temperature variation is part of the reason why the storms that we do see don’t materialize into major events.

Storm Track
Another simple reason for less snow across the metro area: They tend to track too far south. Remember how the jet stream guides where storm systems go? Well, during January, the jet stream steers storms further south toward New Mexico and Arizona. In November and December, the jet stream directs storms closer to us, which is why we sometimes get ample snowfall during those months. Similarly, in February, March, and April, the storm track tends to start to shift further north, bringing more systems and more moisture into our area.

But the mountains get a ton of snow in January, right?
Correct! January is actually one the snowiest months in the high country. In Colorado, our weather is influenced by the polar jet stream and the subtropical jet stream at varying times throughout the year. Since winds within the stream blow from west to east, no matter which jet stream is affecting us on a given day, the originating moisture source comes from the Pacific Ocean. The mountains in Colorado tend to ring out the atmosphere of its moisture, which results in hefty snow during the winter months. On top of that, Colorado is situated centrally to where storms coming in from both the Pacific Northwest (think Seattle) and the Southwest (think Los Angeles) impact snow totals in the mountains.

Average Snowfall in Denver by month
September: 1.0”
October: 4.2”
November: 7.5”
December: 8.1”
January: 6.6”
February: 7.7”
March: 11.4”
April: 8.9”
May: 1.7”

For those hoping for a snow day, you have March and April to look forward to, which are Denver’s snowiest months. Also, just because we don’t normally see much snow in January doesn’t mean it can’t happen. One of Denver’s top 20 snowstorms happened in January. Mind you, that was back in 1883, but maybe that means we’re due for another?