Why Wind Is More Dangerous When the Leaves Are Still on Trees

Trees are vulnerable to powerful storms, even a single gust of wind. While tree damage can occur any time of the year, wind damage is more dangerous in certain seasons.

Fall can be a key season for wind-related tree damage because deciduous trees may still hold their leaves when storms bring strong winds and heavy rain. That’s why anyone who has dealt with mature trees knows how much more movement a leafy canopy creates during a storm.

The reasons leafy trees face more stress during windy weather, and the role wet soil plays, help explain why some fall storms cause serious tree damage.

Why Leaves Make Trees More Vulnerable to Wind

Tree professionals sometimes describe a dense canopy as having a windsail effect. Leaves and branches give the wind more surface to push against, placing extra pressure on the tree.

A video from arborist education account @fruitstitute on Instagram compared a thick canopy to a sail catching wind. Research published in the International Society of Arboriculture’s journal on red maples found that the makeup of a tree’s crown affects how much wind load it experiences.

Trees can reduce some of that pressure naturally. Leaves turn and cluster in the wind, while branches bend and move with gusts.

That doesn’t mean a tree should be heavily thinned before a storm. Pruning needs vary by species and tree condition, so major pruning decisions are best left to a qualified arborist.

Foliage can also increase the amount of wind a canopy catches. For example, an eight-year study of street trees in Rochester, New York, showed that most branch failures happened while the trees were in leaf.

Why Wet Soil Makes Trees Easier to Uproot

Wet ground can add another risk during a windstorm. After heavy or prolonged rain, saturated soil may hold tree roots less securely. The U.S. Forest Service notes that saturated soil and shallow roots can make trees more vulnerable to being uprooted by wind.

Penn State Extension also notes that trees may begin leaning or uproot when wet soil can’t hold the root system securely. Raised soil around the roots can be one sign of movement. A full canopy catching strong wind while the roots sit in soaked soil can create a difficult combination for a tree.

Why Fall Windstorms Can Cause More Tree Damage

Fall storms can arrive before deciduous trees have dropped their leaves, leaving a full canopy exposed to strong winds. If rain has already soaked the ground, the tree may also have less support around its roots. The combination can increase the chance of broken branches, leaning, or uprooting.

A tree’s condition still matters. Decay, root damage, weak branches, and earlier storm damage can all affect how well it handles high winds. After a storm, homeowners should stay clear of trees with new leaning, lifted soil, cracked limbs, or hanging branches. Penn State Extension recommends professional assessment when a damaged tree could threaten people or property.

Sources

• Instagram user @fruitstitute, “Video”
• International Society of Arboriculture, “The Effects of Pruning Type on Wind Loading of Acer Rubrum”
• International Society of Arboriculture, “The Effect of Pruning on Service Requests, Branch Failures, and Priority Maintenance in the City of Rochester, New York, U.S.”
• International Society of Arboriculture, “Wind-Thrown Trees: Storms or Management?”
• Penn State Extension, “What to Do About Leaning Trees”
• U.S. Forest Service, “Windthrow”

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