Tapping maple trees usually occurs in late winter and early spring. In Wisconsin, March is a prime month for tapping sugar maple trees and this is when the sap is sweetest. But, only about 2 percent of the sap is sugar, so it has to be boiled down to remove the water and increase the sugar concentration.
Weather is a crucial factor for a good harvest of maple sap for syrup. Good weather conditions for syrup production are nighttime temperatures in the 20s and sunny days with temperatures in the 40s. This alternate freezing and thawing temperature cycle causes pressure changes inside the tree that makes the sap flow. If the nighttime temperatures are too cold, it takes a longer for the sap to warm up and “run” in the daytime. If the temperatures are very cold, the sap may not run at all. If the nighttime temperatures are too warm, the sap will not flow.
Our March weather has been terrible for harvesting sap for syrup. Minimum temperatures throughout Wisconsin were 10 to 15 degrees above normal, and maximum temperatures soared into the 70s and 80s.
Tree species have adapted to different climate conditions, particularly temperature and moisture. Sugar maple trees don’t live in geographic regions where summer temperatures frequently reach 100 degrees or where the winter temperatures regularly drop below 0 degrees. In the United States, the best climate conditions for sugar maple trees are found in the northeastern and north central regions of the country. Unfortunately for maple syrup lovers, the Northeast has also experienced warm weather this March.