It was just 10 months ago that Boston smashed its all time snowfall record [7], and the US was blanketed in freezing weather from west to east as the Polar Vortex unleashed cold air for the second year in a row. It was so cold, the GDP report for the winter period had to be double-seasonally adjusted [8]as the sharp economic slowdown, which was blamed on the "harsh weather", simply did not make sense otherwise.
Fast forward to today when according to AccuWeather [9], Christmas felt more like Memorial Day across much of the eastern United States as temperatures rose between 20 and 35 degrees above average and 5-15 degrees above previous record highs.
While unlikely that it was the hottest Christmas ever - temperature recordings only go so far - records were broken all along the Eastern Seaboard, from the Southeast to New England with some areas breaking their previous record high by more than 10 degrees F. Some records were broken from the 1800s.
The highs that occurred on Thursday are more typical of late spring and early summer.
More from AccuWeather:
"One of the most impressive records on Christmas Eve occurred in Burlington, Vermont, when the city set their all-time December high temperature," AccuWeather Meteorologist Brian Lada said.
Burlington rose to 68 F on Christmas Eve, 17 degrees higher than the previous record of 51 F set in 1957. The all-time warmest day prior to Thursday in Burlington was on Dec. 7, 1998 and Dec. 5, 1941 when it reached 67 F.
As a result of the warm weather, the entire Northeast was left without a white Christmas. The only location which saw at least an inch of snow accumulation on the ground on Christmas was across northern Maine. "Records also fell all along the Interstate 95 corridor from Boston through Washington, D.C.," Lada said.
High temperatures rose into the 70s on Christmas Eve along the Interstate 95 corridor from New York City to Washington, D.C. Boston was 1 degree shy of reaching the 70-degree mark.
The warmth is expected to continue, and will lead to this December being the warmest on record across many Eastern cities. Through Christmas Eve, temperatures are more than 10 degrees above normal for the month across much of the Ohio Valley and Northeast.
[10]
Following a modest cooldown on Saturday, a push of milder air will build across the East on Sunday and will cause cities to challenge records yet again. "New York City and Baltimore are some of the cities that could break records yet again on Sunday before a cold front washes away the warmth," Lada said.
Just as last year's unprecedented cold had a specific catalyst, namely an abnormally active Polar Vortex, so this year's record hot weather is due to two things. As explained last week [11], typically this time of year, Arctic Oscillation would bring cold air to the Eastern U.S., bringing temperatures down. But so far this year, the oscillation has stayed much farther north, allowing warm air from the south to fill the void.
[12]
The other factor is El Niño, a periodic climate cycle in which sea surface temperatures over the eastern Pacific become warmer than usual. The effects from changes in Arctic Oscillations generally last only a few weeks, but the balmy weather in the Northeast could continue because of the El Niño effect, experts say.
We'll leave the discussion of whether the weather anomalies of the past three years are due to global warming, or "climate change", as it is now known, to others, but we will ask: if the past two years saw GDP boosted by 1.5% on average in the winter [8]as a result of abnormally cold weather, does that mean that the US economy, which according to the Atlanta Fed was "growing" at 1.3% net of the record heat, is already in a recession?
