Winter Is Losing Six Weeks a Century
Define seasons by warmth, not the calendar, and Central Park's spring now clears 40°F on Feb 20 — 27 days earlier than the 1869-1898 average of Mar 18.
Pick a date for spring and you can argue forever. Let the thermometer pick it — the day the smoothed daily mean first crosses 40°F — and the answer stops being a matter of opinion. In the first 30 full years of the record (1869-1898), that day averaged March 18. In the most recent 30 (1996-2025), it averages February 20.
That is 27 days earlier. Nearly a month of February now behaves like the old March.
The seasons themselves have stretched and shrunk. Spring (the warming climb between a sub-40°F winter and a 68°F-plus summer) ran 80 days in the early record and runs 101 now — a gain of 22. Summer (mean above 68°F) added 14 days, from 97 to 111.
Winter paid for all of it. The cold season — mean below 40°F — has fallen from 113 days to 72, a loss of 41 days. That is the headline: the warm seasons gained 36 days between them, and winter lost more than either of them gained.
A skeptic could blame the method — a smoothed-mean threshold is a choice. So check it against frost, which doesn't care how you define seasons. The last spring freeze (low at or below 32°F) has slid from April 11 to March 30; the first fall freeze, from November 9 to November 22. The frost-free season grew from 212 days to 238, up 26.
Two independent measures agree: spring arrives earlier, fall lingers later, and the cold middle is being squeezed from both ends. The city stands +4.5°F above its 1870s baseline.
The record's warmest year is 2023; its coldest is 1888 — a 135-year span between the extremes. The seasons aren't sliding on the calendar. They're being redrawn by the temperature, and winter is the line giving way.