An Extraordinary December

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In his “Autumn Hymn,” Richard Newell observed:

Soon shall all the songless wood
Shiver in the deepening snow…

Instead, December 2015 unveiled an entirely different scenario. Large parts of North America, Europe, and Asia basked in unseasonable warmth. In North America, as wave after wave of warmth washed over the Continent, the “deepening snow” did not come and the “songless wood” did not “shiver.” Rather, the verse of Alice Lord’s “Indian Summer’s Aftermath” much better described what happened in the New York City area:

O dreamy days that linger
With trace of summer yet!
So soft, so mild, so mellow…

O peaceful days and golden!
Ye call back summer flowers…

Larchmont12132013-2b
Blooming roses

The result was a record-breaking December for the New York City area.

December2015Summary

Day after day of the finest temperatures of spring or autumn, depending on one’s preference, saw this year smash the existing record for warmest December by 6.7°F (3.7°C). The second largest difference between the most extreme monthly average temperature and second most extreme monthly figure is 2.8°F (1.6°C).

December2015Graph

Statistically, December’s average temperature of 50.8°F (10.4°C) was 3.075σ above the normal average, making it a once-in-950-year event.

Numerous daily record high minimum and maximum temperature records were set or tied.

Record High Maximum Temperatures:
December 13: 67°F/19.4°C (broke record of 64°F/17.8°C, 1923)
December 14: 67°F/19.4°C (tied record of 67°F/19.4°C, 1881)
December 15: 68°F/20.0°C (broke record of 67°F/19.4°C, 2008)
December 24: 72°F/22.2°C (broke record of 63°/17.2°C, 1996)
December 25: 66°F/18.9°C (broke record of 64°/17.8°C, 1982)

Record High Minimum Temperatures:
December 11: 50°F/10.0°C (broke record of 48°F/8.9°C, 1971)
December 12: 55°F/12.8°C (broke record of 53°F/11.7°C, 1899)
December 13: 55°F/12.8°C (broke record of 51°F/10.6°C, 1991)
December 14: 53°F/11.7°C (tied record of 53°F/11.7°C, 2001)
December 15: 53°F/11.7°C (broke record of 48°F/8.9°C, 2001)
December 17: 50°F/10.0°C (broke record of 48°F/8.9°C, 1984)
December 24: 63°F/17.2°C (broke record of 50°F/10.0°C, 1931)
December 25: 57°F/13.9°C (broke record of 50°F/10.0°C, 1979)

The low temperature of December 24 tied the previous record high temperature for the date. It set a new monthly record for the warmest minimum temperature recorded in December. It is the highest minimum temperature registered in the November 10-March 27 timeframe.

In addition, for the first time on record, which goes back to 1869, December had no days on which the temperature fell to 32°F (0.0°C) or below. The previous fewest days on record for December was 6 days. That record was set in 1984 and tied in 2006. There are only 10 cases in November that had 0 days on which the temperature fell to freezing. Moreover, the 11 days on which the minimum temperature stayed at or above 50°F (10.0°C) smashed the record of 5 days set in 1982 and tied in 1998. It also matched the November record for most such days.

December 2015 was so warm that it would have ranked just above November 1999 as the 9th warmest November on record. Even more remarkable, it was warmer than Octobers 1876, 1888, 1889, and 1925.