Crozet Weather Almanac: December 2015


December Was The Warmest December Ever

By Roscoe Shaw and Heidi Sonen

December 2015 Weather
December 2015 Weather

No matter how we slice and splice the data, December was the warmest ever.  Not just for December, but for all months compared to the normal for the time of year.  The average temperature was 50.4 degrees, which was astonishingly above the long-term average of 38 degrees.  January of 1932 held the old record at 11.1 degrees above normal.

As a statistician, I’m hard to impress.  Winter months have bigger anomalies.  Bigger extremes.  Surely there must have been another month, when adjusted for seasonal variability, that was more abnormally warm.  So, I divided all the months by their standard deviation (have I lost you yet?) and the answer was the same:  December was the warmest ever.

This was an impressive record because I have 1267 months in my database.  That’s more than 105 years.  Not only was it warm here, but the earth as a whole likely set a record for the warmest month ever.

El Niño is a naturally occurring cycle that warms the earth a degree or so every few years.  This year has been a record El Niño year and the temperatures have surged as warm Pacific waters have bubbled to the surface.  El Niño almost always warms global temperatures, but it is no guarantee of a warm winter in Virginia.  This year is more the exception than the rule.

So is this a sign of impending global doom and runaway global warming?  I doubt it.  As I write this, snow has returned and temperatures are in the teens.  Virginia weather can turn on a dime.  Also, as El Niño wanes, global temperatures will likely be cooler in a couple of years.  So far this century, the global temperatures are up just 0.12 degrees.  That’s one-eighth of a degree.  Most climate models forecast closer half a degree so both Heidi and I remain optimistic that climate change continues to happen much slower than many climatologists have feared.


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