Seasonal Snow and Temperature Forecast for 2025-2026 winter season

08/18/25 7pm: With meteorological fall less than 2 weeks away, this is the time of year when I start thinking about snow and skiing again and what we can expect this winter in terms of above/ below average snowfall and temperatures. Below is my initial seasonal snowfall and temperature predictions for this upcoming 2025-2026 season based on some climate teleconnection patterns and from consulting with good friend and expert CO snowpack climatologist: Trevor G.

I decided to keep it a bit more simple this year, breaking up CO into 4 main zones (in terms of seasonal impacts), but obviously there is great variation in each of these zones so take the predictions with a grain of salt. And of course seasonal forecasts (especially this far out) are ripe for error! So the outlook may change some as we get closer to winter.

I’m basing my forecast on a weak La Nina from now through January, then likely turning neutral after that, combined with a negative PDO (Pacific Decadal Oscillation) and the negative phase of the Pacific-North American Index (PNA). I also consider other factors like the MJO and NAO, etc. Here are the main drivers:

• ENSO Phase: currently neutral (anomaly of -0.1 degC) but predicted to trend towards weak La Nina (anomalies of around -0.4 to -0.6 by Nov/Dec), then trending towards neutral again by Feb-Apr (-0.3 to 0.0 anomalies in the spring).

• PDO: Negative Phase. Cooler SSTs along the North American coast and warmer SSTs in the central North Pacific (cooler than normal in the eastern Pacific and warmer than normal in the western Pacific). The forecast indicates that this negative phase is expected to continue for the remainder of 2025 into 2026.

• PNA: currently near neutral, possibly turning more negative by Nov-Jan. The positive phase of the PNA pattern tends to be associated with Pacific warm episodes (El Niño), and the negative phase tends to be associated with Pacific cold episodes (La Niña).

  
  

So these teleconnections generally favor heavier snowfall over northern CO and less snowfall over southern CO (maybe similar to last season). And favors near/below average snowfall on the front-range with outbreaks of cold air moving in from the north.

It is useful to look at some analogs with some examples for northern and southern CO (using areas around Vail and Wolf Creek as examples). Below are some analog years in which we had a weak La Nina paired with a negative PDO:

• 1995-1996: Monster year for north-central mountains (near Vail), closer to average for Wolf Creek (but still below)

• 2005-2006: Above average for north-central mountains near Vail (including a big start to the season: Nov-Jan). Below average near Wolf Creek / San Juans, but southern mountains caught up some towards end of season.

• 2008-2009: Above average year near Vail (near 350”), Wolf Creek / San Juans had a big start Nov-Jan but then a dry middle of the winter

• 2016-2017: Huge snowfall season for the north-central mountains (near Vail) and also a big snowfall season for Wolf Creek (well above average across the state)

• 2024-2025: Near/above average snowfall for the north-central mountains especially for areas near Vail to Copper/Breck and Winter Park, very dry mid-winter conditions for San Juans / Wolf Creek with low snowfall

  
  

So my general forecast for Colorado is:

• North-central mountains / northwest CO: near/above average snowfall and near/below average temperatures. Best chances for above average snowfall will be from Aspen, to Vail to Copper / Breck to A-Basin, Loveland, Winter Park, IPW and RMNP (red boxed area on the map).

• South-central / southwest mountains (including Crested Butte, Telluride, Wolf Creek, Monarch): near/below average snowfall and near/above average temperatures. Higher uncertainty in seasonal snowfall. Maybe bigger snowfall in the spring (or a fast start in late fall, followed by a lull).

• Northern front-range / northeast CO (including Den/Bou): near average snowfall, near/below average temperatures. Likely a warm and dry fall through November (but can’t rule out a strong cold-front at some point). Then likely average snowfall through mid-winter with some cold clipper systems. Then maybe some heavier snowfall towards spring time (with neutral conditions developing) and a southern storm track.

• Southern front-range / southeast CO (including Springs, Pueblo, etc): below average snowfall / near average temperatures. Dry fall through Nov. More northerly snow events may limit snow south of the Palmer Divide, but there will be some cold-fronts at times. More active during spring (Mar-May).

  
  

Here is more detailed information about the teleconnections adapted from the web:

Negative PDO (Cool Phase) usually is more favorable for Colorado snow. Tends to be linked with La Niña-like atmospheric circulation, steering more moist Pacific Northwest troughs into the Intermountain West. Brings a colder and wetter pattern to the northern and central Rockies. Historically correlated with enhanced snowfall in places like Steamboat, Vail, Winter Park, and Loveland.

Positive PDO (Warm Phase) is associated with more El Niño–like patterns, which may bring more southwest moisture to southern Colorado (e.g., Wolf Creek), but can also cause dry periods in the central/northern mountains depending on other factors.

For Denver, a negative PDO combined with La Niña typically increases the odds of colder winters with strong Arctic air intrusions.

When these occur together Denver often has average to above-average snowfall potential, especially if strong Arctic air interacts with upslope storms. The I-25 corridor (Denver north into Wyoming) benefits most. Potentially more frequent cold snaps, sometimes prolonged, especially mid- to late-winter the pattern tends to favor clipper-type systems and upslope snow events, not necessarily huge multi-day blizzards, but frequent medium-sized storms.

La Nina falls are typically warm and dry across much of CO. The heavier, more consistent snowfall for the mountains may hold off until mid-Nov or later. During the winter, La Nina drives more zonal, northwest flow over CO so we typically get above average snowfall over northern / central CO and below average snowfall over southern CO (but that is not always the case).

With the more zonal flow this can lead to more downslope wind-events for Den/Bou and the front-range during winter (windy and cold but not big snowfall sometimes during La Nina).

Other factors include the MJO (Maddien-Julien-Osccilation): an eastward-moving pulse of tropical convection (rainfall and thunderstorm activity) near the equator that circles the globe in ~30–60 days. It has 8 “phases” depending on the location of the strongest convection.

These phases alter the jet stream and storm tracks downstream. During certain phases the MJO tends to strengthen and displace the North Pacific jet stream into the western U.S. This increases storminess across the Rockies, enhancing snowfall potential in Colorado.

The MJO can amplify or suppress El Niño/La Niña impacts. For example, in an El Niño year, an active MJO in favorable phases can supercharge storm activity into the central Rockies. During La Niña, the MJO can sometimes temporarily break the typical northern-shifted storm track, allowing better snow setups for Colorado. MJO dominant phase for the winter is uncertain

The North Atlantic Oscillation (NAO) typically has more impact on the east-coast. But the negative phase can allow much colder air to move out of the arctic and into the central U.S. / midwest to eastern CO and east. The positive phase typically traps colder arctic air further north (and is warmer for CO). The current phase of NAO is slightly negative, but hard to tell what it will be this winter.

Finally a little break down For Colorado winters (from Chat):

• ENSO (El Niño/La Niña) → strongest driver of snowfall patterns.

• PDO and AMO → can modulate storm tracks longer-term.

• MJO → modulates storminess on weekly to monthly scales.

• NAO → mostly modifies the background pattern, with secondary effects compared to the Pacific-driven teleconnections.

  
  

That is all for now. What are your thoughts on the seasonal outlook? Do you have any questions for Trevor G and myself? As we get closer to winter, I’ll be updating the outlook based on what I’m seeing.

First image is my initial 2025-2026 winter outlook. Second image shows the different PDO and ENSO phases. Third image shows a depiction of the mid-winter jet-stream during La Nina years from NWS. Image 4 shows current ENSO SST forecast from CFSv2 climate model. Image 5 shows ENSO probabilities over the next year. Images 6 and 7 show Snowpack Timeseries comparisions for the analog years for Colorado Headwaters (Vail area) and Rio Grande Basin (Wolf Creek area). Images 8 and 9 show where the ENSO (La Nina / El Nino region is) and the PDO region.

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