Door County residents who have been braving this week’s deep freeze might also be hearing surprising pops and cracks in the woods, and it’s not just the wind. In extreme cold, a curious natural phenomenon can occur when freezing temperatures cause trees to suddenly split or “explode.”

Victoria Holderer, an applied research ecologist at The Ridges Sanctuary in Baileys Harbor, says that while rare, trees can “basically explode” under the right conditions and timing. “Trees contain sap, a mixture of water and nutrients, and when temperatures plummet far below freezing, that sap can freeze and expand, creating intense pressure inside the bark and wood.” Holderer explains that “when the pressure becomes too great, the trunk or large limbs can crack suddenly and loudly, sometimes sounding like a gunshot or a booming echo through the forest.”

That’s exactly the kind of weather Door County has seen this week, with dangerously cold lows and wind chills dipping well below zero, and forecasts calling for continued bitter cold through the rest of the week and into the upcoming weekend, making conditions ripe for frost cracks in trees.

“Trees don’t literally explode, but the loud cracking and splitting of bark is very real and is a reminder of how harsh winter conditions can be on the landscape here on the Peninsula,” Holderer added.