It happens in an instant, a flash, a crack of thunder, and then silence. The storm passes, and everything seems intact. But the next day, you notice bark scattered at the base of your tree, a long scar running down the trunk, or a spiral pattern of damage wrapping around it.
When a thunderstorm rolls through, trees often take the brunt of the impact. One of the most alarming things a homeowner can see afterward is a tree with bark blown off, long scars running down the trunk, or very commonly a spiral pattern of damage wrapping around the tree.
Lightning damage can look dramatic, subtle, or even misleading. Some trees fail immediately. Others appear fine, only to decline months or years later. Understanding what lightning does to a tree helps you know when to act and when to keep a close eye on things.
Why Trees Get Hit by Lightning
Trees don’t attract lightning in the way many people think, but they are natural targets because they:
• Are tall and exposed
• Contain a significant amount of moisture
• Are connected directly to the ground through their roots
When lightning strikes, the electrical energy must travel somewhere, and a tree provides multiple pathways.
How Lightning Travels Through a Tree
Along the Outside of the Tree
Often, lightning travels along the surface of the bark, especially when it is wet from rain. This can cause bark to peel away in strips, split vertically, or fall off days or even weeks later.
Even when the damage appears mostly cosmetic, the living tissue just beneath the bark may be killed, interfering with the tree’s ability to transport water and nutrients.
Through the Inside of the Tree
In some cases, lightning moves through the tree’s internal tissues. Sap heats instantly and turns to steam, expanding with explosive force. This can result in large sections of bark being blown off, deep cracks forming in the trunk, and structural weakening or immediate failure.
Trees with high moisture content are especially vulnerable to this type of damage.
The Impacts Lightning Strikes May Have on a Tree
Damage to Branches and the Canopy
Lightning does not always travel straight down. It can jump between branches or exit the tree at high points. Signs of this pattern include dead or scorched limbs, sudden leaf drop, or dieback that appears weeks later.
Canopy damage is sometimes delayed, making it easy to underestimate the severity of the strike.
Root and Soil Damage
A large portion of the electrical energy often exits the tree through the roots and disperses into the surrounding soil. This underground damage is easy to miss but extremely important.
Root damage can lead to:
• Reduced water uptake due to feeder root loss
• Decreased stability from structural root damage
• Increased likelihood of failure during wind events months or years later
What to Look for in the First 30 Days After a Lightning Strike
The first month after a lightning strike is critical. Some damage is immediate, while other issues develop gradually. Watch for the following:
• Bark Changes
Bark may loosen, curl, or begin to fall off. Fresh cracks or splits in the trunk may become apparent, and spiral or vertical scars may become more visible over time.
Bark that peels away weeks later often indicates underlying tissue death.
• Leaf and Canopy Response
Look for sudden browning or wilting of foliage, leaves dropping out of season, or individual branches failing to leaf out. Damage may appear uneven or isolated at first.
• Branch and Limb Issues
Watch for hanging or cracked limbs, new dead branches in the canopy, or branches that snap more easily during wind events.
• Soil and Root Zone Signs
Soil heaving or cracking near the base of the tree, fungal growth near roots, or a noticeable lean that wasn’t present before are all important indicators.
Root damage often shows up subtly so keep a close eye on changes at ground level.
• Insect Activity
Stressed trees are highly attractive to pests. Watch for increased wood-boring insect activity, sawdust-like material on the bark or ground, or birds concentrating on damaged areas of the trunk.
• Delayed Symptoms
Be aware of bark drying and shrinking, oozing sap or dark streaks on the trunk, or a general “off” appearance compared to nearby trees.
What to Do After a Lightning Strike
Some trees recover well, while others decline over time. A tree may leaf out normally the following spring and still be compromised.
• Have the tree evaluated by an ISA Certified Arborist
• Do not assume survival based on outward appearance
• Monitor the tree over multiple growing seasons
• Address safety risks early, especially when trees are near structures or high-use areas
In some cases, lightning protection systems may be appropriate for valuable or historic trees, but a professional assessment should always come first.
Lightning damage isn’t always loud or immediate. Sometimes it leaves a dramatic spiral scar. Other times it quietly compromises a tree from the inside out. What begins as a single flash and a crack of thunder can leave behind damage that unfolds long after the storm has passed.
If you suspect a tree on your property has been struck by lightning, a professional assessment can help determine the level of risk and the best course of action.
