US winter has shrunk by more than one month in 100 years

Scientists find that climate change has helped push first frosts later across the country

The length of the US winter is shortening, with the first frost of the year arriving more than one later than it did 100 years ago, according to more than a century of measurements from weather stations nationwide.

The trend of ever later first freezes appears to have started around 1980, according to data from 700 weather stations across the US going back to 1895 and compiled by Ken Kunkel, a meteorologist at the National Oceanic and Atmospheric Administration's National Centers for Environmental Information.