April In Vermont Hottest On Record, Part Of Long Stretch Of Warm Months

View of my yard in St. Albans, Vermont, this morning
May 1. Spring is way ahead of scheduled after a 
record warm month of April. 

 At least as measured in Burlington, this April was the hottest on record, with data going back more than 130 years.  

The mean temperature for the month in Burlington was 50.6 degrees. This beats the previous record set in 1945 for warmest April by a full degree. Which is kind of impressive. A warmest month is fairly rare, but becoming more common with climate change. Usually, though, when we do manage to break a record monthly high, it's by a couple tenths of a degree.

The Aprils of 1945 and 2023 were quite similar in that they both featured a spate of record highs reaching into the 80s during the second week in the month. 

In 1945, there were four days in row with temperatures in the 80s from the 10th through the 13th.  In Burlington, it reached 88 degrees on April 13, easily the hottest for so early in the season. There was another record high of 85 degrees this year on April 15. Plus a non-record high of 83 on the 16th. 

Same view of my yard exactly one year ago, May 1, 2022.
You can see how much further ahead with spring we are this
year. And last year was a very early spring, too! 

In both 1945 and 2023, the second half of the month cooled off significantly.  But the second half of April, 1945 was much colder than the corresponding weeks in 2023.  In that month near the end of World War II, it got as cold as 24 degrees and some days never got above 50 for highs. 

In the month just ended, there were no freezes and every day got to at least 50 degrees and several days topped. 60.  That's how we beat out 1945.

To nobody's surprise, April was much warmer than normal in other reporting sites in and near Vermont. Most were at or near the top of the list for warmest April.

Precipitation was much closer to normal than temperatures. Burlington measured 2.81 inches of rain, which was just a quarter inch below normal. Northern Vermont was a little bit on the dry side for April, while southern Vermont was a little on the wet side. 

MORE THAN A YEAR OF WARMTH

Average temperatures for a month are calculated based on all the averages for the 30 years ending in 2020.  Using that method of measuring, the last time we had a "cooler" than average month was September, which was marginally on the chilly side.

However, those 30 years ending in 2020 were quite a bit warmer than previous decades, due to the effects of  climate change. It truly is a "new normal"

I like to judge how warm or cool a month was based on what were considered average temperatures for the second half of the 20th century. 

If you look at it that way, the last time we had a cooler than average month was in January, 2022.  Which would mean we've had 15 consecutive months of above average temperatures, at least as measure in Burlington. 

Spring greenery has come much earlier than normal in
Vermont due in large part to the hottest April on record,
at least as measured in Burlington. 

Last year was the fifth warmest on record in Burlington, Vermont. This year is so far on pace to beat that, but of course the year is still young. A lot could change. 

Without climate change, the averages would be a roll of the dice. Generally speaking, half the months would be on the cool side, the other half warm. 

This doesn't mean we'll never again have a cooler than average month. Even compared to the 20th century average. I guarantee we'll have a cold month here or there moving forward. 

But the dice are now loaded. They're weighted toward warm. So from now on, the chances of having a month that is warmer than than the 20th century average is definitely greater than it being on the chilly side. 

You see real world effects of all this.  I've never seen trees in Vermont blossom into leaf as early as I've seen this year. Lawn care companies started mowing weeks earlier than normal. Since it's only the beginning of May, we can still have hard freezes. If that happens, apple and other fruit crops would be in jeopardy.

The good news is that at least for the next few days, though it will be cool and dreary and wet, the chances of frost are quite low. But who knows what will happen later in the month?

Not only has the weather become warmer, it's also more erratic. The roll of the weighted dice can be damaging with this new climate regime.