Science says, Jack Frost nipping at your nose later and later

Winter is coming … later. And it’s leaving ever earlier.

Across the U.S., the year’s first freeze has been arriving further into the calendar, according to more than a century of measurements from weather stations nationwide.

Scientists say it is another sign of a changing climate, and it has good and bad consequences. There could be more fruits and vegetables — and also more allergies and pests.

“I’m happy about it,” said Karen Duncan of Streator, Ill., near Chicago. Her flowers are in bloom because she’s had no frost this year, just as she had none last year at this time.

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 per cent of the lower 48 states have had a freeze as of Oct. 23, compared with 65 per cent in a normal year, according to Jeff Masters, meteorology director of the private service Weather Underground.

Duncan’s flowers should be dead by now. According to data from the weather station near her in Ottawa, Ill., the average first freeze for the 20th century was Oct. 15. The normal from 1981 to 2010 based on NOAA computer simulations was Oct. 19. Since 2010, the average first freeze is on Oct. 26. Last year, the first freeze in Ottawa came on Nov. 12.

Last year was “way off the charts” nationwide, Kunkel said.

Overall, the U.S. 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.