December is looking much colder than last year—and likely snowier

Without El Nino, the weather should be more typical than 2015.

Boston, MA - 12/29/2015  - A woman makes her way through the snow in the Boston Public Gardens in Boston, MA, December 29, 2015. Keith Bedford/Globe Staff)
A woman makes her way through the snow in the Boston Public Garden on December 29, 2015. –Keith Bedford/Globe Staff

There are very few things I will ever guarantee in weather, but making a prediction about this December’s temperatures in comparison to last year’s is something upon which I am willing to stake my meteorological reputation.

The fact is, it will be colder than last year, and by a pretty wide margin. Of course, some massive shift in the sun might overheat us this coming month—anything is possible—but short of that, it’s time to prepare for a different December than the one we had a year ago.

If you forgot about the end of 2015, let me remind you: It reached nearly 70 degrees on Christmas Eve and was in the 60s on Christmas Day. I won’t soon forget having Christmas dinner at a friend’s house, enjoying hors d’oeuvres outside!

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It’s going to be a much colder December this year mostly due to the lack of El Nino. When we experience a year with a strong El Nino—meaning warmer-than-average water temperatures off the coast of Peru—temperatures in much of North America are warmer than average for the winter, especially December. The map below helps to convey just how warm December 2015 was.

December 2015 was a very warm month across much of the globe
December 2015 was a very warm month across much of the globe. —WeatherBell Analytics

While there is conflicting information about just how cold it will get during the final month of 2016, all of the models agree that there will be at least a few days of colder-than-average weather and that, overall, the month looks to be within a degree or so of average. It might end up a bit colder than normal or a bit warmer, but it’s not going to be a super warm month like last year.

December temperatures are looking closer to average this year
December temperatures are looking closer to average this year. —WeatherBell Analytics

You’re probably also interested in snow. Snow is a very difficult thing to forecast in any year because one major coastal storm can quickly raise snowfall averages. Alternatively, a couple of missed storms or a rain-snow line that moves inland can leave the ground bare through Christmas.

Even different versions of the same model don’t agree on where the heaviest snow will fall. The image below shows just how divergent the various ensemble members of the CFS v2 are with regard to snowfall through December.

Various versions of the GFS are in disagreement where the heaviest snow will fall in December
Various versions of the CFS V2 are in disagreement as to where the heaviest snow will fall in December. —WeatherBell Analytics
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The other piece of the puzzle is the fact that we are still in a drought. While we could see significant snow even in a drought year, it’s less likely.

There is still a dry signal to the precipitation pattern in December 2016
There is still a dry signal to the precipitation pattern in December 2016. —Weatherbell Analtyics

My bottom line for this year: You should expect a colder December, which is more typical of New England. Additionally, the threat of snow will be higher than last year. What’s likely is near-average or perhaps above-average snowfall, especially across ski country.

I will continue to update my thoughts on the coming winter on Twitter @growingwisdom.

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