This year, a warm winter has allowed syrup producers in states like Maine, New York, and Wisconsin to start collecting sap as early as January.
But some farmers think the warm weather might actually be terrible news — leading to less sap and a possible syrup shortage later this year.
Experts say it's still too early to tell, though there is cause for concern. Abby van den Berg, an assistant professor at the University of Vermont's Proctor Maple Research Center, explains that sugaring season typically occurs when very precise temperature conditions unfold — periods where the nights are freezing and the days thaw out.
The reason: When warm temperatures arrive during the day, pressure builds and squeezes the sap out of the tree. Then when temperatures dip back below freezing at night, that draws moisture back into the tree, allowing it to produce sap again. So you need a string of freezing nights and above-freezing days, alternating back and forth.
This year, the sap is arriving earlier — potentially bad news
This year, warm weather has arrived much earlier. And if the high temperatures stay around, that's potentially concerning.
If there aren't enough periods of freezing nights followed by warm days, van den Berg says, there's the risk that not enough sap will flow from the trees.
What's more, she says, a string of really warm days will create metabolic changes in trees that further affect sap flow — and could disrupt production even if temperatures do cool again later this spring. While this could potentially affect yields, she says it's too early to tell.
"The season starting early is not a sure indicator of how the season is going to be overall," echoes Winton Pitcoff, coordinator for the Massachusetts Maple Producers Association.
How sugaring season usually works
Sugaring season — the time of year when maple syrup is made — typically runs from around mid-February through early April, though it can vary year by year. It all depends on when the sap starts flowing. (Typically it takes 40 gallons of sap to make one gallon of syrup.)
The particular conditions that cause the sap to run often arrive at different points in the year. "Last year, we really didn't have a serious run until late March. And then it ran for three weeks, and it was an excellent season," Pitcoff said.
And farmers generally know they have to prepare for anything. "For the most part, maple producers know that they're going to have to be flexible with what Mother Nature deals to them," van den Berg added.
The one encouraging sign this spring is that there's a lack of snow on the ground. Pitcoff points out that the lack of snow means farmers have an easier time heading into the woods to set up their lines for sap collection.
In the end, we won't know how bad the warm weather is for sap collection until later this year. And it's probably too early to worry. Last year at this time, everyone was worried about overly cold weather, and the Northeastern region ultimately produced 2.96 million gallons of syrup, up 7 percent from the year before.
"In maple production, when you freak out is toward the end of the season when you realize that things are going to turn out badly," van den Berg said. "But we don't know. We just don't know until it actually happens."