Reference
Ye, H. 2001. Increases in snow season length due to earlier first snow and later last snow dates over North Central and Northwest Asia during 1937-94. Geophysical Research Letters 28: 551-554.
What was done
The author analyzed first and last snowfall dates for 139 stations throughout north central and northwest Asia for the period 1937-1994.
What was learned
Statistically significant positive trends of snow season length were found over much of the area studied, with most of the stations having a trend "higher than 4 days per decade." The increase in snow season length, according to the author, "can be attributed more to earlier snowfall than to later last snowfall," although both phenomena played a role in the overall lengthening of the snow season.
In the mean, the results of this study indicate a lengthening of the snow season of somewhat more than 23.2 days over the 58-year period. Since the mean snow season length of the stations studied ranged from 60 to 260 days, this increase in snow season length amounts to an extension of anywhere from 10 to 40%, which is huge!
What it means
The author notes that his finding is "contrary to a general assumption that the length of the snow season would have decreased due to increasing surface air temperatures." Perhaps that says something about the assumption that surface air temperatures are rising!