Weather in Aspen in December

The month to avoid. Of the twelve, December is the one to avoid. Highs sit at -0.8 °C and the day is short; this is an indoors-with-excursions month, not an outdoors-all-day one.

December ranks 11 of 12 — near the bottom of Aspen's year. June is the month that works, and the swing between the two is 75 points, which is a different holiday rather than a slightly better one.

Rain on 11 days, 1 of them heavy. Enough to need a plan B, not enough to need a plan around it. Layers, and a genuinely waterproof outer — at -0.8 °C the difference between a good day and a miserable one is entirely down to what you are wearing.

What the averages hide

Averages flatten a month, and this one hides a few things: 31 nights drop below freezing, so anything left outside stays frozen. Across the twenty years measured, the hottest December day reached 12.2 °C and the coldest night fell to -27.2 °C, and the wettest single day dropped 38 mm — roughly 73% of the month's rain in one day.

December is statistically steady but not small: the year-to-year variation is modest in relative terms, yet the wettest December on record still delivered 104 mm against 16 mm in the driest. In a month this wet, even a tame spread is a lot of rain in absolute terms — the 52 mm average is a reasonable planning figure, not a promise.

Wind is light at 3.5 km/h, so the temperature on the page is close to the temperature on your skin, and humidity runs at 89%, which at -0.8 °C means damp rather than muggy — the kind of cold that gets into a coat and stays there.

How December sits in the year

Temperatures hold steady either side: 5.7 °C in November, -0.8 here, -0.9 in January. Nothing about the timing within the month matters much.

Daylight in December

December sits at the dark end of Aspen's year — 9.4 hours of daylight against 14.9 at midsummer, holding steady all month. Sightseeing days are genuinely shorter, and an itinerary built for summer will not fit.

An inland climate

With no coast nearby, the year swings a fair way — 39.6 °C between the warmest afternoons and the coldest nights, wider than any coastal city at this latitude would manage. At 2405 m, altitude is doing as much work here as latitude: thinner air means fierce sun by day and heat that leaves the moment it sets.

How busy it gets

Off season. The genuine off season: cheapest by a distance, with the caveat that some tours and restaurants close entirely.

Crowd levels are estimated from climate desirability and school-holiday calendars, not from visitor numbers.

December in Aspen versus nearby

If Aspen is one option among several, the nearby comparison is worth making. Denver is a better bet in December — 8.7 °C warmer, 6 days less rain. Moab is a better bet in December — 8.5 °C warmer, 5 days less rain.

So: December is a compromise. June is 73 points better and is what Aspen is actually like at its best — worth moving the trip for if that is possible, and worth adjusting expectations for if it is not.

Every month in Aspen

See all twelve months in Aspen, or where else to go in December.