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dave epstein

Here’s why this weekend’s weather was some of the craziest you’ll ever see for January in Boston

Saturday’s balmy temperatures brought people outside in Boston, including in the Public Garden.
Saturday’s balmy temperatures brought people outside in Boston, including in the Public Garden.John Tlumacki/Globe Staff/Globe Staff

We knew that this weekend was going to be warm. We knew that this weekend would break record temperatures. But despite the anomalous forecast, this weekend’s weather has been even more extreme by some measures than expected.

Saturday’s temperatures averaged 31 degrees over the 30-year normal. It’s very rare to ever see a 30 degree anomaly such as this. Many meteorologists were scratching their heads about the last time something like this occurred.

January 2020 hasn’t seen one 24-hour period of below freezing temperatures in Boston. (NOAA)
January 2020 hasn’t seen one 24-hour period of below freezing temperatures in Boston. (NOAA)

Before colder air begins to filter into Southern New England later Sunday afternoon, it’s worth noting that February 2018 featured two back-to-back 70 degree days — the first time ever that had been recorded for two consecutive days in the winter season.

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And it happened again Sunday Boston reached a high of 74 degrees, making for the second pair of 70-degree days during meteorological winter.

Extreme overnight warmth

Low temperatures are recorded based on 24-hour numbers, so Saturday night’s extreme overnight warm will not be reflected in the record books because by the time we get to midnight tonight it will be lower than 60 degrees. That said, the summer-like night we just experienced has to be one of the warmest overnights ever recorded for January — if not the warmest. A new high record was set Sunday in Boston before the sun even came up.

The official temperature in Boston stayed in the mid-60s Saturday night and early Sunday. (NOAA)
The official temperature in Boston stayed in the mid-60s Saturday night and early Sunday. (NOAA)

In addition to the warm temperatures it also was slightly muggy this morning with the dew point around 60 degrees. This is also at the top of the heap for January. High humidity like this in winter just doesn’t happen in most years.

Putting the warmth in perspective

Saturday’s high and low temperatures were exactly average for Orlando, Fla., on Jan. 11th. If you look at the entire month to date, the weather in Boston has been more typical of Norfolk, Va. More and more, we are living through small periods of weather in all seasons, especially winter, that average for parts of the East Coast hundreds of miles south of here.

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This weekend’s warmth is typical for central Florida in mid-January. (NOAA Data)
This weekend’s warmth is typical for central Florida in mid-January. (NOAA Data)

Amazingly, another 70 degree day in January

As the morning showers cleared, a strong westerly wind followed. This has prompted the National Weather Service to issue a wind advisory. Strong westerly winds will helped drive the air down from the Worcester hills into Boston. When this happens, the air tends to warm up a little bit and this is what propeled us to another 70 degree day. This is the second pair of back-to-back 70 degree days during meteorological winter and the first ever in January.

Things will turn colder

Obviously this warm weather isn’t going to last. Already we see half a foot of snow across northern Maine on Sunday morning and below-freezing temperatures are approaching Portland. Sunday afternoon as the sun sets, this cold will be arriving in Southern New England.

A jet stream moving south will put us back on track for colder weather during the week ahead, although temperatures will still average milder than mid-January normals.

The end of the third week of January and into the fourth week are starting to show signs of colder temperatures — possibly colder than average with the potential for some snow. But there is almost no way January 2020 won’t end up as a warmer-than-normal month. It’s just a matter of where in the record books we’ll be after the next 19 days.

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Changing climate continues to show itself

I’ll end this piece with a final image for you to consider. The chart below shows all the record temperatures since 1872. Obviously the beginning of this chart has a lot of records because back then everything would have been a new record.

However, what you should focus on is the past 40 years and the lack of cold temperature records. Unless there’s an awful lot of incorrect scientists out there, this weekend’s taste of late spring is just a preview of a slowly evolving pattern in which more unusual warmth will be interrupting our coldest season.

 Low temperature records are becoming less and less frequent over the past decades. (NOAA Data)
Low temperature records are becoming less and less frequent over the past decades. (NOAA Data)