I have been collecting snowfall data from North American ski areas since 1992, with some data reaching as far back as the late 1960’s. Summary data for 116 locations are on my website bestsnow.net and I have over 80 of these every year since 1989, over 60 since 1982 and over 30 since 1973. The first chart weights equally 8 ski regions, 7 in the West and one in the East.
The 8 regions have similar lift served ski acreage and the areas with data cover about 90% of both ski acreage and skier visits.
Some people began inquiring about ski area snowfall trends in the late 2000’s, and at that time my data going back to the early 1970’s showed no trend either on an overall basis or at the regional level. From 2001-2013 worldwide temperatures increased at about ¼ the rate predicted by the climate models. Temperatures increased sharply from 2014-16 and with further recent increases are in line with the climate models, projecting near term increases at a rate of about 0.2C per decade.
While there is strong scientific consensus upon rise in temperatures since 1970 and that those increases will continue under current assumptions, there is very little consensus that the climate models can accurately predict clouds, precipitation or regional climate nuances. Therefore I continue to examine the snowfall data I receive each season.
As shown in the first chart there is still scant evidence of any decline in snowfall at North American ski areas. The next table lists the areas where I have the most data, usually over 50 years.
The bold numbers are 2000 and later snowfall averages and standard deviations as a percent of 1999 and prior. The key points are that both numbers are slightly lower since 2000, which means that snowfall volatility (or whiplash) is not increasing. With precipitation not necessarily affected by the rising temperatures (and there are arguments precipitation could increase), I believe the focus of study should be upon whether and where there might be more rain and less snow.
In interior ski regions of North America rain is sufficiently rare that any impact upon snowfall lies decades in the future. One could argue that the Colorado Rockies with their high altitude resort elevations are more insulated from climate change than any other ski region in the world.
So I narrowed my focus to the ski regions that have always experienced significant rain, those being the Northeast and the lower elevations along the West Coast. Here’s the Northwest since 1971.
Note the cluster of high La Nina snow years in the early 70’s.
For a long term perspective, here’s AltaGuard Utah since 1946.
It would show more of a decline starting in 1970 or 1980, but not when you include the lean 1953-63 seasons.
The ~1C increase in temperatures should translate to an average increase in the rain snow line of about 500 feet. In practice it’s not so simple.
- The rain/snow line, like all weather phenomena, is volatile by season and by individual storm within a season.
- The ~1C temperature increase since 1950 is a worldwide average and may be larger, smaller or even nonexistent is particular locations. It’s well known to be far larger in most of the Arctic for example.
- The temperature increase in a particular location may not be evenly distributed seasonally. In interior continental locations the temperature rise is more in summer. That would explain why alpine glaciers in Europe and North America are retreating even though winter snowfall may not be declining at all.
Here’s California, flat trend but lots of volatility.
From 1988-2019 the Central Sierra Snow Lab measured an exact daily split between rain and snow.
2013-2018 had high rain incidence. This was particularly destructive in 2013, 2014 and 2015 when snowfall was only half normal.
Further rain vs. snow analyses are based upon the ratio of total water to total snow. As season averages increase above 15% and particularly 20%, increasing rain incidence can be presumed. In the West Coast locations in lower middle ski area range, the ratio of total water to total snow is increasing gradually despite no evidence of declining snowfall. Here’s Alpine Meadows since 1971 in same climate zone as CSSL.
2019-2023 in the Sierra had rain incidence more in line with prior history.
In one location that is very low in ski area context, Government Camp, Oregon, the ratio of total water to total snow is climbing more rapidly.
25% to 35% means a lot of rain, but Government Camp is below most Oregon ski area bases and gets 245 inches vs. 452 1,500 feet higher at Hood Meadows.
Move up to higher elevation at Crater Lake and the rain/snow trend is trivial.
Pacific ski areas with sufficient altitude like Mammoth, Kirkwood, Mt. Rose, Bachelor and the Whistler alpine so far have minimal impact from rain.
One location with a recent negative trend is Alyeska. Here I compare mid to top elevation snowfall.
As of 2019 this data set looked like a huge global warming signal. Each of the 5 years 2015-2019 had a lower proportion of mid to top snowfall than any of the prior 32 years. 2025 was another wet year after 4 better ones.
The Northeast is more complex with an overall slight declining trend in snowfall over the past 50 years.
In the Northeast latitude and distance from the Atlantic are probably at least as important as altitude in determining rain incidence. The trend for increasing rain incidence is less at the eastern locations I studied than at lower West Coast locations.
Here’s Pinkham Notch, the pass between Tuckerman Ravine and Wildcat ski area.
Overall rain incidence 20-25% is comparable to the lowest ski areas on the West Coast, and it is extremely severe 45% during the shoulder season months of November and April.
Very prominent in the data are the unprecedented levels of rain vs. snow in the Northwest in 2014-15 and in the Northeast in 2015-16. It is not unreasonable to assume that such outlier seasons may become less rare as temperatures increase further.
What about SoCal? Here’s L.A. rainfall since 1978, extremely volatile but no real trend.
Note 1944-64 with 10 years under 10 inches rainfall, not the good old days as that means less than 80 inches mountain snowfall. Snowfall since 1969 is my unofficial estimate based upon monitoring ski reports as data is scattered and often not reliable.
Even more unofficial is my count of rain days in the ski areas since 1978.
I am skeptical of whether models can predict changes in weather patterns. One prediction is that latitudes in the lower 30’s may become drier. Taos snowfall supports this view though the data starts in its record high 1972-73 season and ends with its second lowest.
However L.A. rainfall is not declining and neither is Arizona Snowbowl’s snowfall. It’s hard to come up with a meteorological explanation why New Mexico would be getting drier when SoCal and Arizona are not. But my gut feeling from living in SoCal is real. The Southern California mountains are downwind from an urban heat island with 15 million people in it—and I just suspect that’s not good. The areas closest to L.A., Mt. Waterman and Mt. Baldy, seem most affected by increasing rain vs. snow.
At latitudes 33-35 in South America, drought since 2010 is more severe than in the American Southwest. Portillo is the latitude of San Diego, lower than every US ski area except Mt. Lemmon near Tucson.
Portillo volatility is extreme. If you extend data back into the late 1950’s (using a nearby mining site), you find another drought period similar to what we see in Alta snow and L.A. rain.
Despite the outlier examples I’ve cited, in the case of the Western United States, I push back and say strongly—our children and grandchildren are going to be enjoying these same ski areas with, overall, not very different conditions than we’ve seen in our times.
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