After a warm fall, it’s about to get really cold in Boston

An air mass from the Arctic is headed to New England.

Boston Fall Weather
Foliage continues to change along the Commonwealth Avenue Mall near the Samuel Morris Statue in Boston. –CJ Gunther/EPA-EFE/REX/Shutterstock

After Monday’s unseasonably high temperatures nudging 70 degrees, the weather pattern has undergone a dramatic shift over the past 24 hours. Here’s a look at what’s in store this week.

Cold air mass — followed by an even colder one

Meteorologists give air masses specific names to represent the type of air they contain. On Monday, we experienced maritime tropical air, which is warm and somewhat humid. A cold front swept that air mass out to sea and a new air mass from Canada known as continental polar air sat over the region Tuesday morning.

A small area of low pressure will ride along this divide overnight and could even bring a few light showers around Boston, or perhaps even a wet snowflake or two over the interior. There’s a higher chance of light rain for Cape Cod and the islands.

A warm weather record?

Advertisement

Wednesday and Thursday will feature seasonable temperatures and a good deal of sunshine. The mornings will be cold with temperatures around the freezing point, creating sunrise frost on the ground. Boston still has yet to go below 40 degrees this season, tying the longest stretch of days above 40 at 201 days. If we don’t go below 40 through midnight Tuesday night, we will break the record. Worcester continues to be freeze-free, but that will end on Friday.

Wintery cold makes an early debut

On Friday, another air mass — this one straight from the Arctic — will push into the region.  Continental Arctic air will bring temperatures more conducive to January than early November to close out the week. We haven’t seen any real cold air this season, so not only is this unusual in any year, it’s highly unusual this year. The loop below shows temperatures over 20 degrees below average sweeping into New England Friday.

via GIPHY

As the arctic front sweeps through, there may be a rain or even snow shower early Friday morning as winds will pick up and temperatures fall. The high temperature Friday is likely going to be reached at midnight because by the time we get to Friday afternoon, temperatures will be hovering in the lower 30s.

Friday Temperatures
Temperatures during the afternoon Friday. —Dave Epstein
Advertisement

On Saturday morning at sunrise, expect temperatures in the 20s with some teens showing up across the region. This is cold enough to freeze the ground, which means that those of you that have field games early Saturday can expect to be playing on very cold surfaces.

If the cold weather doesn’t get you excited about winter, perhaps a little bit of snow in the mountains well as that front passes Northern New England there could be a coating up to an inch of snow in the highest elevations. This is nothing unusual and actually often occurs this time of the year.

Friday Snow
Some light snow accumulation is possible in the highest elevations Friday. —WeatherBell

Milder before Thanksgiving

After this cold snap, temperatures are likely to moderate as we get closer to Thanksgiving, but not to the extent we just saw. Indeed, we should all realize summer can’t last forever.

Weather
It's snowing in parts of Maine
November 13, 2017 | 12:53 PM