Does the late arrival of winter bug you out? Here's why

Wednesday was the coldest day in New York City since March 14th of last winter; with a high temperature in the upper 30s, it certainly feels like December is right around the corner. This past Saturday, on November 25th, we reached a low temperature of 30°, officially recording the first freeze of the season. The average is on November 14th, and it has happened much later; the latest first frost on record in NYC was on December 22nd, 1998! But overall, the first freeze in the Tri-State is trending later and later. The ten latest first frosts in Central Park have primarily happened in the 21st Century, and only two happened before 1950: 

Data from the National Weather Service office in Upton, NY

For those of us who don't love winter's chill, this is not necessarily a bad thing! And it certainly helps with the heating bills as well. But there are negative consequences to a late freeze. 

For example, bugs LOVE it. Deer ticks, which are vectors of Lyme Disease, do not die off until temperatures dip to the teens or single digits. Many deer ticks survive the winter by burrowing underground or finding other protection from harsh temperatures, like piles of leaves. A deep freeze is more likely to kill the eggs of these disease vectors, so a milder winter could increase your chances of encountering ticks carrying Lyme Disease when the weather turns warmer. 

Graphic courtesy of Climate Central

Deer ticks can be active if the temperature is above 34°, so it's important to check for ticks after any outdoor adventure, especially in the woods or tall grass. 

Another warm weather pest, mosquitoes, thrive in hot and humid weather; they're most comfortable with temperatures in the 80s. However, some mosquito eggs (especially Northern species) can survive in areas that later end up under ice or in frozen mud, and adults can hibernate during the colder months. 

Graphic courtesy of Climate Central

The later start to winter allows mosquitoes to stay active longer, and it can contribute to larger populations as well. It takes a prolonged deep freeze to kill hibernating adult mosquitoes and their eggs, assuming that they found a safe spot. And that's just not happening as often in the Tri-State as it used to. The table below shows the number of days below 10° in Central Park since records started in 1869: 

Data from the National Weather Service office in Upton, NY

The most recent year on the list was during the Great Depression. Of course, we are no stranger to very cold winter days, but when it happens, the cold snap is brief and anomalous. This trend is reflected in more recent decades by the rise in average temperatures in New York: 

Winter is the fastest-warming season in NYC. The average temperature is computed for

December, January, and February in this graphic from Climate Central. 

4 degrees may not sound like much, but in the winter, it can be enough to turn a pond into a skating rink. According to an article in Olmsted Now, "Central Park welcomed its first official visitors, the ice skaters" on December 11th, 1858! The idea of ice skating on a natural pond in Central Park is kind of unthinkable today, but it was a popular winter activity for 19th Century New Yorkers.

Image courtesy of New York Public Library

So as we try to shake off winter's first chill in the Tri-State this week, just remember: it used to be a lot colder, for a lot longer, during a typical New York winter. 
This article references reports and materials from Climate Central. Thank you!