Climate Change is Shrinking Winter in the U.S., Scientists Say
As the climate continues to change, the seasons are seeing a shift as well, with winters coming later and leaving earlier than ever recorded.
More than a century of data collected from weather stations across the U.S. shows that the first freeze of the year has been arriving further into the calendar.
Researchers say this is is another sign of the warming climate, and that it has both good and bad consequences. For example, there may be more fruits and vegetables available, but there could also be an uptick in allergies and pests.
The trend of ever later first freezes appears to have started around 1980, according to an analysis by The Associated Press of data from 700 weather stations across the U.S. going back to 1895 compiled by Ken Kunkel, a meteorologist at the National Oceanic and Atmospheric Administration's National Centers for Environmental Information.
To look for nationwide trends, Kunkel compared the first freeze from each of the 700 stations to the station's average for the 20th Century. Some parts of the country experience earlier or later freezes every year, but on average freezes are coming later.
The average first freeze over the last 10 years, from 2007 to 2016, is a week later than the average from 1971 to 1980, which is before Kunkel said the trend became noticeable.
This year, about 40 percent of the Lower 48 states have had a freeze as of Oct. 23, compared to 65 percent in a normal year, according to Jeff Masters, meteorology director of the private service Weather Underground.
Overall the United States freeze season of 2016 was more than a month shorter than the freeze season of 1916. It was most extreme in the Pacific Northwest. Oregon's freeze season was 61 days — two months — shorter than normal.