Kansas Forest Service

Are Trees Really “Exploding” in the Cold?

If you’ve heard a loud crack echo through the woods during recent cold snaps, you’re not alone, and no, trees aren’t actually exploding. The dramatic sound many people are reporting is likely the result of a phenomenon called frost cracking, a condition that’s been around as long as winter itself.

“Exploding trees” is a relatively new phrase making the rounds, but it’s simply a sensational way of describing frost cracks. These cracks occur when moisture and sap inside a tree rapidly freeze and expand during extremely cold weather. As pressure builds within the tree’s tissues, it can release suddenly, causing a sharp, loud, vertical crack along the trunk or large branches. In some cases, the sound can be startling, often compared to a gunshot or firework.

While explosives or lightning can damage trees, those causes are not typically associated with this type of wintertime cracking. Frost cracks themselves can vary in severity. Some are minor and cosmetic, while others may be deep, long, and wide. Although it’s uncommon, pieces of bark or even limbs can occasionally loosen or fall. More often, the concern is structural. Frost cracks can weaken a tree and make it more vulnerable to future stressors like insects, disease, or decay.

The crack in this young tree's bark is likely due to wintertime sun exposure or water freezing withing the tree bark.

Certain trees are more susceptible than others. Much like sun scald, trees with thin bark are at higher risk because sunlight can warm the underlying tissues during the day, only for them to freeze rapidly when temperatures plunge. Species such as maple, boxelder, linden, sycamore, cottonwood, and many fruit trees are particularly vulnerable. Young, developing trees also fall into this higher-risk category.

Hearing a frost crack form can be impressive, and a little unnerving, especially during periods of extreme temperature fluctuation. And let’s be honest: we’re often drawn to dramatic explanations. “Exploding trees” certainly grabs attention. But in reality, what’s happening is a natural response to winter stress.

The tree likely experienced sunscald or frost cracking years ago and has tried to regrow bark to cover the exposed area.

Just yesterday, a loud crack rang out in the woods nearby. It could have been a falling limb, or, given the recent swings in temperature and bitter cold, it may have been the sound of a frost crack forming. Either way, it’s another reminder that trees are living systems, constantly responding to the conditions around them, even in the depths of winter.

Shad Hufnagel
Forest Health Coordinator
Kansas Forest Service