Santa Ana wind events are the single biggest cause of tree failure across the San Gabriel Valley, and they’re also one of the most predictable. They happen every year, mostly in fall and winter, with sustained winds in the 40 to 70 mph range and gusts higher than that. The trees that fail during Santa Anas almost always had warning signs that could have been addressed beforehand – dead limbs, weak unions, root issues, palm hangers, top-heavy canopies that catch too much wind. Prevention is dramatically cheaper than post-event cleanup, and most of the work can be done well in advance of the season.
Here’s the practical guide to prepping your La Verne property before the fall winds arrive – what to look for, what to do, when to do it, and when to call in a professional.
When Santa Ana Season Hits
Santa Ana events can technically happen any time of year, but the peak season runs October through March, with the most damaging events typically in October and November. By the time the first major event of the season hits, your trees should already be prepped – meaning the work needs to be done in late summer through early fall, not after the National Weather Service issues a Red Flag Warning. Once a Santa Ana is forecast, tree services book up fast, and emergency response rates apply.
The 30-Minute Walk-Around
Before you decide whether to hire a professional, spend 30 minutes walking your property and looking at each major tree from a distance. Step back 30 to 40 feet from each tree – far enough that you can see the entire canopy clearly – and check the following:
Look up for deadwood.
- Branches that are bare while the rest of the tree is leafed out.
- Limbs with peeling, missing, or sloughing bark.
- Sections of the canopy that have gone brown or rust-colored.
- Any dead branch larger than 2 inches in diameter – these are the first things to come down in high wind.
- A few small dead twigs are normal. Multiple dead limbs scattered through the canopy, or large dead sections, are not.
Look for hanging widow-makers.
- Limbs that are partially detached but caught in the canopy.
- Broken sections held in place by other branches rather than by structural attachment.
- These are called widow-makers for a reason – they fall without warning and they fall hard.
Check the branch unions.
- Where major limbs come off the trunk, look for tight V-shaped angles (under about 40 degrees) – these often have included bark and weak attachment.
- Compare to healthy U-shaped unions with wider angles and smoother crotches.
- Any visible crack in a branch union is a serious warning. Cracks don’t heal – they get worse over time.
- Codominant stems (two main trunks growing from one base) on mature trees, especially with bark turned inward at the union, are high-risk structures.
Look at the base.
- Mushrooms or fungal conks growing on the trunk or at the base. These indicate active wood decay – by the time you see mushrooms, decay has usually been progressing for years.
- Soft, spongy, or hollow-sounding wood when tapped firmly with the back of a hatchet or a small mallet.
- Vertical cracks running up the trunk.
- Heaving or cracked soil near the base – a sign the root plate is moving.
- A sudden lean that wasn’t there a year ago, especially with freshly exposed roots on the side opposite the lean. This is active root failure.
Inspect palms specifically.
- Old fronds that haven’t released and are hanging straight down – these become projectiles in Santa Ana wind.
- Heavy fruit stalks and seed pods that should have been removed.
- Softening at the base of the trunk (especially on Canary Island date palms and queen palms, where this often indicates fatal disease).
- Trunk angle changes from year to year.
- Fewer new fronds emerging than the previous year, or off-color spear development.
Common La Verne and San Gabriel Valley Species That Fail in Santa Anas
Some species are far more likely to fail in Santa Ana wind than others, and knowing which trees on your property are higher risk helps prioritize:
- Eucalyptus – the most notorious Santa Ana failure tree in Southern California. Whole trees uproot, large limbs shear off, and even apparently healthy specimens can fail with no warning. If you have mature eucalyptus near a structure, get them evaluated.
- Mexican fan palms (Washingtonia robusta) – tall, top-heavy, and prone to dropping fronds and seed pods in high wind. Hangers are a major hazard.
- Coast live oak – generally wind-tolerant, but trees with included bark at major unions can fail catastrophically. Older oaks with structural defects deserve professional evaluation.
- Eldarica pine and Aleppo pine – common in landscaping, with shallow root systems that can uproot in saturated soil during winter rain Santa Anas.
- Pepper trees (California pepper, Brazilian pepper) – brittle wood, weak unions, frequent limb failure.
- Liquidambar (sweetgum) – tall, fast-growing, often with weak structure in landscape specimens.
- Avocado – surprisingly common Santa Ana failures because of dense canopy that catches wind plus shallow root systems.
What to Have Done Before the Season
Once you’ve identified concerns through the walk-around, the right next step is a professional arborist evaluation. Most legitimate tree services offer free consultations, and a 30 to 45 minute walkthrough will tell you which trees need work this year and which can wait. The most common pre-Santa Ana services:
Deadwood removal (crown cleaning).
Removing dead branches throughout the canopy is the single most effective storm-prep work for most trees. Deadwood is the first thing to fail in wind, and removing it dramatically reduces both the failure risk and the potential damage if other parts of the tree do fail.
Weight reduction on long lateral limbs.
Limbs that have grown out long and heavy on weak unions are leverage waiting to happen. Properly placed reduction cuts – shortening lateral limbs while preserving the tree’s natural form – relieve stress on the union without harming the tree.
Cabling and bracing for valuable trees with structural defects.
Mature trees worth preserving but with weak unions can often be saved by professional cabling – installing high-strength steel cable between major limbs to redistribute load and reduce failure risk. This is technical work that requires ISA-trained installation, but for the right tree it can extend safe useful life by decades.
Palm trimming.
Proper palm trimming before Santa Ana season removes dead and dying fronds, heavy seed pods, and hangers. Important note: don’t over-prune palms. Stripping all but a few fronds (the so-called “hurricane cut”) actually weakens palms by removing the live frond mass they need to produce food and reducing wind resistance, despite the name.
Removal of trees too compromised to save.
Some trees with multiple warning signs – mushrooms at the base, hollow trunks, major cracks, advanced lean – are past the point where pruning or cabling will keep them safely standing. Removing them on your schedule before the season is dramatically cheaper than removing them on the storm’s schedule afterward.
When to Schedule the Work
- Late summer through early September – ideal window for pre-Santa Ana work. Crews have availability, weather is workable, and there’s time to schedule larger projects.
- September through early October – still good timing, though tree services are getting busier as the season approaches.
- Mid-October onward – possible but increasingly difficult. Once Red Flag Warnings start being issued, tree services book up and emergency rates start applying for last-minute work.
- During an active Santa Ana – don’t schedule routine work. Save the call for genuine emergencies.
- After a Santa Ana event – for trees that didn’t fail but show new lean, cracking, or other damage, get them evaluated soon since they’re often weakened and vulnerable to the next event.
What to Do During an Active Santa Ana
- Stay indoors and away from trees, especially during the strongest gusts.
- Move vehicles out from under trees if you can do so safely before the event hits.
- Keep pets indoors.
- Bring in or secure loose outdoor furniture, pool covers, and anything that could become a projectile.
- Don’t approach any tree that appears damaged, leaning, or with hanging limbs during the wind event.
- If a tree fails on your property during the event, document it but don’t approach until conditions improve and any contact with power lines has been ruled out.
Get a Pre-Season Evaluation
ArborWorld provides free pre-Santa Ana property evaluations across La Verne and the San Gabriel Valley by ISA Certified Arborists. We walk the property, identify the high-risk trees, and give you a written prioritized recommendation – what needs work this year, what can wait, and what’s fine to leave alone. Call (626) 779-8786 to schedule. 24/7 emergency line available during active events.
