Burlington, Vermont's Longest Ever Streak Of Continuously Above Zero Temperatures Could End This Weekend.

Rime ice on trees on Burlington, Vermont's waterfront on
a subzero morning in February, 2023.  Burlington has, as
of this month, broken a record for most consecutive days
continuously above zero. That streak has a very good
chance of being broken this weekend. 

As of yesterday, Burlington, Vermont has gone - by my calculation, - 661 consecutive days without the temperature going to or below 0 degrees.  

The last time it was zero degrees, as measured at the National Weather Service office in South Burlington, was on February 26, 2023.  

The old record for consecutive days above zero was 654 days between February 22, 2001 and December 9, 2002.

In more than 120 years of records, Burlington has only had two winters in which the temperature never got to zero. 

Those were the winter of 2001-02 and last winter, which was the warmest on record.  The winter of 2001-02 used to be the warmest on record, but we've had four other winters since 2015-16 that were even toastier.

It's just another example of how climate change has affected our seasons here in Vermont. 

WEEKEND SETUP

All big streaks must come to an end, and I'd give the chances of the current continuous stretch of above zero temperatures ending this weekend at about 50/50.

We have a couple factors that favor it.   A weak system should dump an inch or two of snow on Burlington later today through Saturday morning. It will be light and fluffy and not amount to much.  But snow cover helps make clear, calm nights cooler.   

Another factors is that a strong high pressure system will be oriented to pull Arctic air down from northern Quebec. 

Then that high will settle pretty much overhead, especially Sunday night and early Monday.  When that happens, winds tend to die off and skies clear. Which means Burlington has a pretty strong shot at being at or below zero by dawn Monday. 

There's a few factors that might work against it getting below zero.  A thick, deep fresh snow cover is much more effective at refrigerating winter nights than the measly inch or two we're likely to see on the ground in Burlington this weekend. 

Winds stirring through Sunday morning might keep temperatures above zero in the Champlain Sunday morning. By dawn Monday, the core of the coldest air will be beginning to head off to the east, which could prevent a zero degree reading. 

Also, Lake Champlain is still warm and almost entirely free of ice. I don't think the warm influence of the lake will extend all that strongly to the National Weather Service office in South Burlington, which is a few miles inland from the lake.

But the contrast between the warm lake and cold air could generate clouds. If that happens, the clouds would tend to keep temperatures above zero.

So it's a tossup as to whether it will hit zero in the Champlain Valley.  It's a lock for below zero weather in most of the rest of Vermont and adjacent New York and New Hampshire. And Quebec for that matter. 

The coldest hollows of Northeast Vermont and the Adirondacks could be in the teens to near 20 below during this episode.

SUBZERO WEATHER DECLINING

Subzero nights in the Champlain Valley are still routine in most winters, but their numbers are declining. 

Attitudes like that depicted in this cartoon are getting
more rare in Vermont as the number of days that
get below zero are declining. 

Accurate daily temperature records for the winter started in about 1901-02.  In the 88 years between that winter and the winter of 1989-90, only seven winters had fewer than ten days that got below zero.

In the 33 years since then, 13 winters had fewer than ten subzero days. 

It's possible the heat island effect from added commercial development in South Burlington has contributed some to the lack of subzero nights in recent years, but climate change is almost surely having a hand in it, too.

If you're a glutton for punishment and like subzero weather, there's always the possibility we could have a  winter with a lot of 'em.  Some winters will still be cold, depending on weather patterns, with or without climate change.

But as the world heats up,  the chances of seeing a winter with dozens of subzero nights locally here in Vermont  keeps declining. 

The record for the most days that got to zero or colder in one season is 45 such day, back in the frigid winter of 1933-34. In February, 1979, we had 12 consecutive days with temperatures below zero, with the coldest in the streak at 30 below, a tie for the coldest on record in Burlington. 

 I'll almost guarantee we'll never see something like that again.