Spring Leaf Out Just Reaching Vermont, Another Early Arrival Among Many Recent, But Not As Early As Last Year

The National Phenology Network tracks the progress
of first leaf out of early plants like honeysuckle and lilac
as it moves northward in the spring. Blue shows where
leaf out was later than usual this year, red is where it
is earlier than normal.  Leaf out has just begun
to creep into far southwest Vermont, a good 10 days
or so earlier than normal. Click on the map to
make it bigger and easier to see. 

At least by one measure, spring has gotten into at least far southwestern Vermont. 

Every year, the National Phenology Network tracks the first time spring leaves begin to appear on certain species of plants as the season advances northward. 

The earliest spring plant leaves had by yesterday begun to enter the low elevations of southwestern Vermont.  

So by this measure anyway, it's officially springtime in Vermont.   

DEFINING SPRING

I think I owe you some definitions first.  Phenology is the study of the timing and cyclical patterns of events in the natural world. 

The National Phenology Network is basically a clearing house that collect, organizes and shares phenological data to other scientists and the general public. It's a pretty interesting website. 

This network defines first leaf of spring this way:  "The First Leaf Index is based on the leaf out of lilacs and honeysuckles, which are among the the first plants to show their leaves in the spring."

In and near Bennington, that has just happened.  And it looks first leaf will spread up into the Champlain Valley soon, thanks to a mild Monday and Tuesday that juiced the spring season.  I notice honeysuckle is just on the cusp of leafing out, and my lilacs are starting to get pretty close to the edge too.

There will probably be a stall in this process today and to an extent tomorrow as chilly air will prevent much in the way of spring growth. 

However, milder air in the forecast Friday and Saturday will get things moving again. Saturday in particular looks promising as a mild, likely rainy Friday night will lead to a balmy Saturday.

It usually takes a while longer to the leaf out to spread into central and northeastern Vermont, but it will get there.

As you might have seen in posts in recent years, I track these phenology leaf out maps fairly closely every spring. What can I say? I'm a big fan of the season.

EARLY SPRINGS

More often than not, in this age of climate change, leaf out has come earlier than normal in recent years due to warm springs.

The leaf out creeping into southwest Vermont is roughly two weeks early, and that's not even the earlier we've ever seen in recent years. In 2023 it was even earlier, thanks in part to an insane, record heat wave on April 13-16 that year that brought temperatures into the 80s across most of Vermont and 90s in parts of southern New England. 

Leaf out in Vermont was also exceptionally early in 2021.  And it was earlier than average last year and in 2022.

Last year was even earlier than we're seeing now. By April 16, 2024 leaf out had covered all of western Vermont all the way to the Canadian border. 

Tracking leaf out has been interesting this year,  It usually starts in South Florida in late January then begins to spread north. It was later than normal along the Gulf Coast, then a little earlier than average in the northern Gulf States.

A cool spell delayed things and made spring greening a little late in the mid-Mississippi Valley in early March. But once the leaf out reached the Mason Dixon line, it's been earlier than normal all the way up to its current northward extent from  New England to South Dakota. 

The Pacific Northwest is running one to two weeks late with their leaf out. 

The National Phenology Network also tracks bloom times, which uses in large part the time honeysuckle and lilacs bloom. 

The bloom index as of yesterday had only gotten as far as roughly a Washington DC to St. Louis line, so it will be awhile before it gets to Vermont