Hearing Loud Booms Outside? It Could Be Exploding Trees in Michigan

We've seen some really intense cold snaps in Michigan, with frigid temperatures well below freezing, and residents across the state—especially in the Upper Peninsula and northwest Lower Peninsula, have heard warnings about a rare winter occurrence.

Exploding trees.

What “Exploding Trees” Really Means

While it sounds dramatic, it’s actually a real occurrence.

Local weather reports and social media meteorologists have flagged the possibility that Michigan’s deep freeze could lead to “exploding trees.” This is expected when temperatures dip far below zero, which is possible in parts of the Upper Peninsula where sub-zero readings are forecast.

But what is actually happening? It’s not going to be like Hollywood-style explosions, right?

Why Extreme Cold Makes Trees Crack

It actually won’t. It’s a sudden cracking or splitting of the tree trunk or large limbs, sometimes loud enough to startle people nearby.

So why does this happen?

READ MORE: Michigan Is About to Get Frigid—Tips to Keep Warm and Safe

Sap contains water. When temperatures plunge, the water in sap within tree tissues can freeze and expand. Since water expands as it turns to ice, pressure builds in the tree’s vascular system.

The outer bark can chill and contract faster than the inner wood. This differential contraction and expansion creates stress between the layers.

Which Trees Are Most Vulnerable

So the tree doesn’t actually detonate like a bomb. What often happens is a frost crack, which is a rapid separation of wood and bark. Sometimes it’s accompanied by a loud noise due to mechanical stress release.

The trees most affected by this phenomenon are thin-barked trees, trees in open sunlight, or trees that haven’t hardened off before a sudden deep freeze.