Warming temperatures are shrinking snowpack in key Canadian watersheds, study suggests

A record-breaking snow drought in the western U.S. is raising concerns about water scarcity and wildfires next summer. A new Canadian study suggests the conditions could signal a longer-term trend that threatens water supplies for millions across the country.

Snow cover in the western U.S. is well below what it normally is at this time of year, and the lowest ever recorded since NASA’s Terra satellite began monitoring in 2001. 

A warming climate is likely making this more common. The snow deposited in winter on parts of western Canada, and the water contained in that snow, declined from 2000 to 2019, according to the study from researchers at Concordia University in Montreal. 

The areas that saw significant declines made up only three per cent of the country, but affected the headwaters of major rivers in the Canadian Rockies. The study also found smaller declines in other parts of southern Canada, which were not statistically significant on their own.

“But we are still seeing some sort of decline. So when we put them together, we realize that within the 25 major drainage basins that we have in Canada, 14 of them are getting affected,” said Ali Nazemi, co-author of the study and associate professor of engineering at Concordia.

The declines in snow have major consequences for everything from municipal water systems to agriculture, lake water levels and shipping, and wildfire risk in Canada’s forests.

“I often refer to the snowpack, especially in mountain areas, as this natural water tower,” said Kate Hale, assistant professor at the University of British Columbia.

Like human-made water towers, the snowpack stores the water and then releases it when it’s needed the most, she said, and those mountains naturally release the water in the summer when it’s most needed by humans for growing food and other uses.

What’s happening this year with the snow?

The low snow is wreaking havoc on the ski season at major resorts in the region. Slopes across B.C. have had to pause operations or scale back because of the lack of snow and warm weather. Vail Resorts, which owns ski slopes across Canada and the U.S., is reporting one of the worst early season snowfalls at its western U.S. resorts. Its resort in Whistler, B.C. also had a slow start to the season, but improved with snowstorms by the end of December 2025.

Meanwhile, Vancouver is facing its first winter without snow in 43 years.

A snow drought is often caused by a lack of precipitation. But this year, precipitation has been closer to normal — it has just fallen as rain rather than snow, says Alejandro Flores, a professor of geosciences at Boise State University in Idaho, leading to what he calls a “wet snow drought.”

“This is certainly something that is consistent with what we expect in a warming world. We expect a preferential transition away from snow and toward rain.”

Warmer fall temperatures can carry into winter, causing precipitation that would normally fall as snow in December or later to come down as rain. That rain not only fails to build the snowpack, but can also wash away what little snow cover is already on the ground, he said.

Snow cover in the mountains acts as a store of water, holding it until spring and releasing it as the snow melts in warmer months. That meltwater feeds water systems millions of people rely on, as well as forests and other ecosystems.

“So the worry is that some of our forests are going to become water-stressed earlier this year and that potentially increases the fire risk throughout the forests of North America,” Flores said.

Will these trends continue?

Nazemi says the situation this year suggests that the low snow trends affecting the Canadian Rockies are extending south through mountains in the western U.S. His team came up with a new measure to calculate how much water is actually in the snowpack, which they call “snow water availability.” 

They used remote sensing technology from satellites for the more accurate measurement of snow water, examining data from 2000 to 2019 covering Canada and Alaska.

The watersheds most affected by declining snow water were the Okanagan in B.C., the Assiniboine-Red River basin in Manitoba and the Saskatchewan River basin. The declines could also reduce flows in the Fraser River and the St. Lawrence River, which millions rely on for water and hydropower.

Nazemi said declining snow cover has affected water security in the past. In 2015, his team’s data show there was a major drop in winter snowpack in the Rocky Mountains. By summer, central B.C. was in severe drought, prompting water restrictions and a pause in fishing on the Okanagan River to protect fish stocks.

Nazemi pointed to another example in 2012, when a mix of weather patterns led to low snowfall in eastern Canada. That year, water levels on the Great Lakes fell, causing problems for cargo ships trying to navigate the lakes to major ports in Montreal and Toronto.

“We should expect some vulnerabilities that are going to be intensifying in the future,” Nazemi said.

But how quickly those vulnerabilities intensify — and how severe future water shortages could be — still needs further study.

Hale said that studying those impacts will be especially important, because people will have to adapt.

“If we’re receiving water at a time where we don’t necessarily need it and the mountains aren’t acting as a natural water tower anymore, how can we sustain the seasonality of water use?” she said.

“Really what that’s calling for is a reevaluation of how we manage our water.”