Trees and Summer Heat

With summer approaching and the weather is increasingly warmer, you may be wondering if your trees are taking a hit. Nice tall trees add so much to the look of your yard and garden. Not only do they make beautiful fixtures for your property, but they provide valuable shade and wind protection for you and your plants. 

Caring for your trees is just as important as the rest of the outdoor elements around your home. While trees can essentially take care of themselves, when the weather gets extreme, human intervention is sometimes necessary.

Do Trees Have Ways of Cooling Themselves?

As the human body regulates its temperature in hot weather through perspiration, trees cool themselves through a process called transpiration. Trees have small openings in their stems, flowers, and leaves from which water evaporates to cool them down.

The hotter the temperature, the more trees have to transpire to keep cool.

Both human beings and trees can experience heat stress due to dehydration. Trees absorb water from the soil through their roots rather than drinking water, but if the soil is too dry, they have insufficient resources with which to cool themselves through transpiration.

Trees normally stay at a temperature roughly the same as the air around them.

But in a heat wave, they’re often heated beyond the ambient air temperature from:

Sunlight reflected off surfaces around the tree.

Heat radiating from surrounding surfaces and structures.

Hot air movement, such as a hot breeze or convection

(warm air rising).

Heat radiating and/or reflecting from surrounding soil

(exposed soil in full sunlight can reach 140°F!).

High temperatures can damage your trees and cause heat stress.

Heat stress occurs when a tree loses water faster than it can replace it.


Obvious signs are:

·        Wilting of the leaves, irregular yellowing of interior leaves or needles

·        Failure to produce healthy-looking new growth, making the tree canopy look sparse.

·        Rust-colored spots or bumps on leaves

·        Scorching around leaf edges

·        Sap oozing from the trunk, attracting ants or beetles.

·        Dropping leaves


When trees are drought-stressed, they cannot mount a strong defense against insect pests like bark beetles. It may look like the insects are to blame but the underlying cause is the drought weakening the trees’ defensive capabilities.

Many symptoms of heat stress in trees look like signs of disease or drought so if you’re not sure, it’s best to call in a qualified tree care professional.


Although summer isn’t a good time to do major pruning on your trees, do remove any dead or dying branches. This will help prevent infestation by wood-boring insects that could further stress the tree.

Phone: 408-836-9147


Workers Comp. & Liability Insurance, Contractor License #836837