Western Colorado’s December Forecast: What to Expect Now

December is here, and Western Colorado has started the month with sub-freezing overnight temperatures and a round of mountain snow. Winter coats have been dug out of the closet, and many of us are wondering: how cold will it really get this December — and will the snow stick around?

Early winter signals indicate a weakening La Niña pattern, which could mean healthier snow totals for the Rocky Mountains this winter. Keep scrolling to see what the Western Slope’s forecast says about the rest of the month ahead.

December Forecast for Western Colorado

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• Forecast snapshot for Grand Junction, Montrose & Delta: Climate data sites such as Wanderlog and Weather Atlas show December daytime temperatures in Grand Junction between 37 and 39 degrees, while Delta and Montrose will be closer to 35 to 36 degrees. Overnight lows are forecast to dip to around 20 degrees.
• What the season outlook says — and why La Niña matters: Colorado’s Climate Center says conditions late in the year are indicating a weak La Niña. The weaker this system gets, the better Colorado’s chances for a near-normal snowpack by the end of winter.
• What This Means for Valleys vs. High Country: In the Grand Valley and the Uncompahgre Valley, communities like Grand Junction, Delta, and Montrose are likely to experience chilly conditions with occasional rain or snow showers. Historic climate data for the region shows that December is one of the driest months in Grand Junction, with limited snow accumulation compared to the surrounding mountains. Colorado’s highest elevations are always the best bet for accumulating snow. This is essential news for ski resorts, water-supply watchers, and recreation fans.
• The Bottom Line — December 2025 Outlook for Western Colorado: This December, the data indicates cold days in the Western Slope valleys and chilly nights with modest precipitation totals for Grand Junction, Delta, and Montrose by the end of the month. A weakening La Niña raises hopes for mountain snow, but valley residents should prepare for a mixed bag of clear and cold stretches punctuated by occasional snow and rain.

Colorado Precipitation in December

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Did you know Grand Junction averages only 0.6 inches of precipitation? It is not a very rainy period, and it usually brings only light dustings of snow, according to World Weather & Climate Information. Further South in Montrose, monthly rainfall totals are often under 1 inch, with snowfall usually around 6 inches or less, according to Weather-Atlas.

Temperature Swings — Expect Crisp days, Cold nights

During December, Western Colorado temperatures usually swing between the mid-to-upper 30s to nighttime lows near the upper teens for Grand Junction and Montrose. The final month of the year is likely to feature classic winter layering: frost-cold mornings, cool afternoons, and clear-sky nights (that dip below freezing). Residents and tourists alike should prepare big contrast between middays and overnights.

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