If you’ve noticed leaves covering your yard in August, you may be wondering if something is wrong with your tree.

While some leaf drop is a normal response to summer conditions, excessive or early leaf loss can also be a sign that your tree is under stress. Across the Central Peninsula and South Bay, August is often one of the hottest and driest months of the year. Urban heat, compacted soils, drought, and insect activity can all take a toll on mature trees.

The good news is that early leaf drop doesn’t always mean a tree is dying. The key is understanding what’s causing it and addressing the underlying issue before the stress becomes more severe.

At West Coast Tree Care, our ISA Certified Arborists help homeowners identify the cause of summer leaf drop and recommend science-based solutions that support long-term tree health through proactive Plant Health Care programs.

Why Trees Drop Leaves During Summer

Leaves require a tremendous amount of water to stay healthy. When a tree cannot supply enough moisture to all of its canopy, it may begin shedding some leaves to conserve energy and reduce water loss.

This is a survival strategy that allows the tree to focus its resources on the healthiest branches and root system.

Summer leaf drop is especially common when trees experience:

• Extended hot weather
• Dry soil conditions
• Compacted soils that limit water absorption
• Heat reflected from pavement and buildings
• Root damage from nearby construction
• Previous years of drought stress

Many neighborhoods throughout San Jose, Palo Alto, Mountain View, Los Altos, Redwood City, and surrounding communities experience these conditions each summer.

When Is Leaf Drop Normal?

Not every fallen leaf is cause for concern.

Some healthy trees naturally shed older interior leaves during late summer as they redirect energy toward new growth and prepare for seasonal changes.

Normal summer leaf drop usually looks like:

• Leaves falling primarily from the interior canopy
• Overall canopy remaining full and green
• No large dead branches
• No signs of pests or disease

If the canopy still appears healthy and vigorous, occasional leaf loss may simply be part of the tree’s natural cycle.

When Leaf Drop Signals Tree Stress

If large sections of your tree are thinning or dropping leaves, it’s worth having the tree evaluated.

Signs that indicate a problem include:

Leaf Scorch

Brown, crispy edges often develop when the tree cannot move enough water to the canopy during hot weather.

Yellowing Leaves

Leaves turning yellow before autumn may indicate nutrient deficiencies, poor root health, or watering issues.

Thin Canopy

Noticeably fewer leaves than previous years often suggest the tree has been under stress for some time.

Premature Leaf Drop Throughout the Tree

If leaves are falling from the outer canopy rather than just the interior, the tree may be struggling with drought stress, root problems, or pest activity.

Dead Twigs and Branch Tips

Dieback combined with leaf loss is a sign that professional inspection is warranted.

Common Causes of August Leaf Drop in the South Bay

Heat and Drought Stress

Even if you’ve been watering, prolonged high temperatures can overwhelm a tree’s ability to replace lost moisture.

Trees growing in lawn strips, parking areas, or heavily paved neighborhoods often experience higher soil temperatures that accelerate stress.

Improper Watering

One of the most common issues our arborists see is shallow, frequent watering.

Trees benefit from slow, deep watering that reaches the entire root zone rather than light daily irrigation near the trunk.

Soil Compaction

Healthy roots require oxygen as much as water.

Compacted soils make it difficult for roots to absorb both, reducing the tree’s ability to support a full canopy during summer.

Construction Damage

Excavation, trenching, or heavy equipment near trees can damage roots months before symptoms become visible.

Leaf drop is often one of the first signs.

Nutrient Deficiencies

Trees growing in poor urban soils may simply lack the nutrients needed to maintain healthy foliage during periods of environmental stress.

Deep Root Fertilization can help improve soil health and strengthen root systems over time. West Coast Tree Care recommends annual fertilization programs to improve resilience and long-term vitality, particularly for trees affected by drought stress or soil compaction.

Summer Stress Can Attract Insects

Stressed trees are often more attractive to damaging insects.

In the South Bay, pests such as the Invasive Shot Hole Borer (ISHB), Red Turpentine Beetle, and Eucalyptus Longhorned Borer are more likely to attack weakened trees.

By improving tree vigor through proper watering, soil care, and Plant Health Care treatments, homeowners can often reduce the risk of serious pest problems.

Monitoring trees during August allows issues to be caught before they become more difficult to manage. West Coast Tree Care identifies ISHB, Red Turpentine Beetle, and Eucalyptus Longhorned Borer among the region’s significant summer pest concerns.

How to Help Your Tree Recover

If your tree is dropping leaves this summer, a few proactive steps can make a significant difference.

Water Deeply

Water slowly around the drip line so moisture reaches the deeper root system.

Add Mulch

A layer of organic mulch helps moderate soil temperature and conserve moisture.

Keep mulch several inches away from the trunk.

Improve Soil Health

Compacted or nutrient-poor soils often benefit from:

• Deep Root Fertilization
• Air tool soil decompaction
• Vertical mulching
• BioHydration treatments during drought conditions

These services help improve root function and support healthier canopies over time.

Schedule a Professional Inspection

Many causes of summer leaf drop look similar from the ground.

An ISA Certified Arborist can determine whether the issue is environmental, insect-related, disease-related, or simply part of the tree’s normal seasonal cycle.

Early diagnosis allows for more effective treatment and helps preserve valuable mature trees.

When to Call an Arborist

Contact an arborist if you notice:

• Significant leaf drop in August
• Entire branches losing foliage
• Leaves turning brown or yellow rapidly
• Bleeding bark or small insect entry holes
• Thinning canopy compared to previous summers
• Dead limbs developing alongside leaf loss

Early intervention often provides the best opportunity to reduce stress and support long-term tree health.

Frequently Asked Questions

Why is my tree dropping green leaves in August?

Healthy green leaves dropping during summer usually indicate stress rather than seasonal dormancy. Heat, drought, soil compaction, or root problems are common causes.

Is it normal for oak trees to lose leaves in summer?

Some interior leaf drop is normal, but widespread leaf loss or canopy thinning should be evaluated by an ISA Certified Arborist.

Can drought cause trees to lose leaves early?

Yes. During prolonged dry periods, trees may shed leaves to reduce water demand and improve their chances of survival.

Does Deep Root Fertilization stop leaf drop?

Deep Root Fertilization does not immediately stop leaf loss, but it improves soil health and root function, helping trees recover from stress and become more resilient over time.

Should I be worried if only one branch is losing leaves?

Yes. Leaf loss isolated to one section of the canopy may indicate localized root damage, insect activity, disease, or branch decline and should be inspected.

Keep Your Trees Healthy Through the Summer

A few fallen leaves in August may be perfectly normal. But when leaf drop becomes excessive or is accompanied by thinning canopies, discoloration, or branch dieback, it’s often your tree’s way of signaling that it needs help.

At West Coast Tree Care, our ISA Certified Arborists provide professional tree inspections and science-based Plant Health Care programs designed to improve soil health, strengthen trees, and help them withstand the challenges of summer in the Central Peninsula and South Bay. Our approach emphasizes preservation, proactive care, and long-term tree vitality whenever possible.

Contact West Coast Tree Care today at 408-351-6155 to schedule a professional tree inspection and help your trees stay healthy through the rest of the summer.