More snow is melting during winter across the West, a concerning trend that could impact everything from ski conditions to fire danger and agriculture, according to a new analysis of 40 years of data.

Researchers found that since the late 1970s, winter’s boundary with spring has been slowly disappearing, with one-third of 1,065 snow measurement stations from the Mexican border to the Alaskan Arctic recording increasing winter snowmelt. While stations with significant melt increases have recorded them mostly in November and March, the researchers found that melt is increasing in all cold season months — from October to March.

Their new findings, published today in Nature Climate Change, have important implications for water resource planning and may indicate fewer pristine powder days and crustier snow for skiers.

«Particularly in cold mountain environments, snow accumulates over the winter — it grows and grows — and gets to a point where it reaches a maximum depth, before melt starts in the spring,» said Keith Musselman, lead author on the study and research associate ,at the Institute of Arctic and Alpine Research (INSTAAR) at the University of Colorado Boulder.

But the new research found that melt before April 1 has increased at almost half of more than 600 stations in western North America, by an average of 3.5% per decade.

«Historically, water managers use the date of April 1 to distinguish winter and spring, but this distinction is becoming increasingly blurred as melt increases during the winter,» said Noah Molotch, co-author on the study, associate professor of geography and fellow at INSTAAR.

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Materials provided by University of Colorado at Boulder. Original written by Kelsey Simpkins. Note: Content may be edited for style and length.