If you watch a holiday movie, you’re probably used to snow-covered Christmases and hot cocoa near a toasty fire. But if you live along the Eastern Seaboard, it may seem that the past few Christmases have been unseasonably warm. We dug back through the data. You’re not imagining things.

Over the long term, climate change is warming the holiday season. But in the major cities we examined, the holidays are warming faster than the winter as a whole.

Boston reached 62 degrees on Christmas in 2015. That was close to a record at Logan Airport, where official observations are taken. But at the Blue Hill Observatory just a few miles to the southwest, the mercury climbed even higher.

“The new record high temperature was set at 10 A.M. this morning when 62 degrees was recorded,” wrote the Blue Hill weather observer, “beating 61 degrees set just one [year] ago [in 2014].” Christmas 2015 had a high of 64 degrees, while Christmas Eve soared to 67. The former broke a record that had stood since 1889.

The 60s even made it up to Maine on Christmas in 2015, where Portland ended up with a record high of 62. New York City hit 62 and 66 in 2014 and 2015, respectively. Christmas eve was 72 degrees in New York City in 2015.

Washington D.C. enjoyed a steamy 69 degrees on Christmas in 2015. And Atlanta hit 75 degrees on Christmas in 2015, and 74 in 2016. Those were the two warmest Christmases in the city’s recorded history.

If we define the week leading up to Christmas to be Dec. 19 to 25, we can see that the past few years have frequently seen highs well above what’s average for this period.

Take New York City for instance. The average high for the week of Dec. 19 to 25 is 41 degrees, based on 1981 to 2010 data. Fourteen years since 2002 have seen at least one day with a high temperature of 55 degrees or more during that week. Temperatures exceeded 70 degrees during that week in 2013 and 2015, the only times on record that has happened. Records in New York City date back to 1869.

Washington, D.C. has climbed into the 60s during the week before Christmas seven out of the past eight years. Philadelphia has made it to at least 65 degrees during that week four out of the past six years.

In Boston, you’re twice as likely to see a high of 55 degrees or more during the week before Christmas now as you were back in the 1930s.

In New York City, the average high temperature during Christmas week is warming by about 0.4 degrees per decade. That doesn’t sound like much, but it’s an increase of nearly 2.4 degrees since 1960. That’s just a hair above the overall winter warming of a little over 2 degrees since then.

Christmas week in Boston is warming even more quickly – roughly 5 degrees since 1960. That is substantially faster than the rest of the winter is warming (which is, in itself, rapid warming).

In Washington D.C., five of the 12 warmest Christmas weeks on record have occurred in the past decade. The nation’s capital has warmed by 5.6 degrees during Christmas week since 1960. Philadelphia’s holidays are warming even more rapidly – by 6.4 degrees since 1960.

That’s a shift equivalent to moving from Philadelphia to Raleigh, North Carolina, for the end of December. Nearby Salisbury, Maryland’s holidays have spiked 4.2 degrees in the past 60 years.

Winter as a whole has warmed a little under 3 degrees in Philly, 2.1 degrees in Washington D.C., and a degree in Salisbury during the same time frame.

In Atlanta, the warming has been more tame – Christmas week has heated up by 2.5 degrees in the past six decades.

Of the eight major East Coast airports we looked at, seven – Boston, Philadelphia, Washington D.C., Baltimore, Salisbury, Raleigh and Atlanta – experienced Christmas week warming that was twice as rapid as the rest of the winter (or more). Only New York City did not, but their holidays were still warming disproportionately fast.

As there are many more locations in the Mid-Atlantic and Northeast where temperatures are measured, this analysis is neither exhaustive nor conclusive, but strongly suggestive of unusually strong warming in the holiday period.

The holidays are warming at rates far outpacing overall climate-driven winter warming, particularly in the Mid-Atlantic. Why? Without a detailed study, it’s impossible to determine specific causes.

In the cities we examined, it’s unlikely the magnitude of the warmth is entirely random because if we change the time period we look at or remove several of the high-end outliers, the resulting warming still outpaces general wintertime warming. However, the unusual intensity of the warmth over the past decade or so, which probably is somewhat random, may have nudged the rate of temperature increase to the high side.

Thanks to some chilly weather expected the second half of this week, temperatures in the Mid-Atlantic and Northeast this year in the week leading up to Christmas may end up close to average. But, by around Christmas Eve and Christmas Day, it may – yet again – be rather mild.

Winter is the fastest-warming season in the United States, and in the Northeast, winter has warmed at a rate that’s three times faster than summer, according to an analysis of temperature data by the research and journalism group Climate Central. That analysis found that winter temperatures in New York City have warmed by 3.2 degrees between 1970 and 2019, for example.

Of the 242 stations the group examined, 190 had winters that warmed by at least 2 degrees since 1970. The greatest warming occurred in colder climates, including Burlington, Vermont; Concord, New Hampshire; and Milwaukee.


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