Extreme April Heat In Vermont/New England Might Lead to Crop/Garden/Forest Damage

Earlier than ever. Green leaves were starting to make an
appearance behind my St. Albans, Vermont house this
morning while a lilac bush in the foreground leafs
out and gets ready to bloom. Record heat this past
week as pushed spring into the too-soon category.

When I got up this Sunday morning, some of the early growing trees behind the house shimmered with tender new green leaves. The lilac bushes were brimming with tiny floret buds, ready to put on a show. 

I've never seen that kind of thing happen so early in Vermont.  It's truly remarkable.

This spring had been proceeding at a fairly average, comfortable, pedestrian pace, until the unprecedented early season heat arrived this week. 

Western Vermont won the heat prize Saturday. In Burlington, the record high Saturday was 85 degrees, breaking the old record of 82 set in 2003,

Everything springtime related leapt ahead far ahead of schedule. Things are where they should be around the first of May.  This race through spring will continue today with temperatures that will be far, far above normal again today. 

The summer party ends tomorrow with sharply cooler air.  Long range forecasts are suggesting that the second half of April might actually be chillier than normal.

If this cooler air is just kind of chilly without hard nighttime freezes, that will be good. It will just slow down the progress of spring and start to bring us more in line with where we should be.

Light to moderate freezes, temperatures that stay at or above, say, 28 in the Champlain Valley and in the mid 20s or better in much of the rest of northern Vermont between now and early May probably wouldn't cause much damage. Unless these readings are accompanied a lot of wind. 

 But it can get as low as the teens this time of year in most of the Green Mountain State that would be a disaster.

This coming week won't be a disaster, despite a particular chill in the air Tuesday and Wednesday. At least we'll get a little rain out of this shift to colder weather.  We need it. 

There's a good chance we'll have  widespread frosts and freezes Wednesday night, but I really doubt it will get cold enough to cause any real harm. 

This budding lilac floret, pictured here on April 22, 2021,
froze to death and never bloomed after a late season
snow and freeze that year. This highlights the danger of
what could happen if spring growth comes too soon.

However, if you brought your tender planters outside to enjoy the warmth, you'll need to bring them back indoors this week. 

My hibiscus has enjoyed the warm sun this week, for instance, but I'm locking it in the house and turning up the heat a bit when it gets cold starting this week. 

In the short term, we're safe, but I don't know how cold it might get in late April. 

These strange spring heat waves have already led to sometimes disheartening, or even costly damage.

A record early heat wave in Vermont back in 2002 brought the earliest 90 degree reading on record to Vermont on April 17 the year. Leaves on trees started coming out almost as soon as they are this year. 

Late in the month, hard freeze destroyed garden plants, and blackened swaths of forest by killing the early leaves. The visible damage lasted well into June before new leaves grew.  Trees being forced to re-leaf stresses them, in much the same way that spongy caterpillars did in Vermont last year and the year before,

Trees can usually withstand on year of defoliation, but if it happens year after year, it takes a toll. 

Other times, the damage from weird early heat is not so costly, but just a little depressing. 

Early spring, 2021 was warm and things were blooming early.  On April 21 that year, lilac trees were already displaying budding florets, and crabapple trees were just starting to bloom. 

Then a snowstorm and harsh freeze hit northwestern Vermont.  Some of the crabapple trees never really bloomed that year as a result. Many of the lilacs ended up stunted, only partially blooming.  Living without the annual spring display of full-blown lilacs was surprisingly depressing. 

Climate change has brought too-early heat waves that encourage too-early spring growth frequently in recent years. Sometimes, in the eastern United States, this has brought widespread agricultural damage, as the Southeastern U.S. saw in 2012 and 2017 and to a lesser extent earlier this year. 

That's not to say freezes are guaranteed to ruin our Vermont spring this year. The fact that it has come too early, though, leaves us prone to trouble. The best bet is just to hope for normal late April weather once this heat wave finally dies after today.