Getting Your Phoenix Yard Ready for Monsoon Season

Quick answer

To get a Phoenix yard ready for monsoon season, make sure water flows away from the house toward retention areas, clear drains and channels, stabilize rock and decomposed granite that wash out, avoid over-thinning trees, and water trees deeply so roots hold. After storms, pause irrigation until the soil dries and check for damage. Check with your city before changing grading or working near a wash.

Last updated October 22, 2026

Monsoon season is the most dramatic weather of the year in the Phoenix metro. Months of dry heat give way to humid weeks with dust storms, strong winds and short, intense thunderstorms. A single storm can wash rock into the street, flood a patio, or knock over a tree. The National Weather Service treats roughly mid-June through September as monsoon season in Arizona, and the time to prepare your yard is before it starts.

Why monsoon storms do so much damage

The problem isn't total rainfall. Phoenix averages about 7 inches of rain a year at Sky Harbor, and the monsoon accounts for only part of it. The problem is intensity. Heavy rain falls on dry, hard soil and pavement, much of it runs off instead of soaking in, and it concentrates quickly. Caliche close to the surface makes this worse because water can't move down. Strong outflow winds ahead of storms put stress on trees and anything loose in the yard.

Step 1: Know where your water is supposed to go

Many Valley lots and subdivisions were designed with retention areas: shallow, often grassy or gravel depressions in front or back yards meant to hold storm water. Others drain to the street or to common-area basins. Look at your plat or HOA documents if you can, and watch the next storm. Water should move away from the house and into those areas, not toward the foundation or a neighbor's wall.

Don't fill or build in a retention area without checking with your city and HOA.
Keep openings in block walls (sometimes called scuppers) clear so water can pass through as designed.
Make sure soil and rock slope away from the house and haven't built up over time.

Step 2: Deal with roof water

Many Valley homes have no gutters, so roof water pours off at the eaves in a line along the house. That water digs trenches in rock beds, splashes soil onto walls, and can soak areas next to the foundation. Options include gutters with downspouts directed to a safe area, splash blocks, rock-lined drip edges, or buried lines carrying water away. Where roofs drain through scuppers, check that water lands on rock or a pad rather than bare soil.

Step 3: Stabilize what washes out

Decomposed granite paths wash out easily. Stabilized DG, edging, or larger rock in low spots helps.
Channels and swales should be lined with larger rock or rip rap where water concentrates.
Slopes should be covered with plants, rock or erosion-control material rather than left bare.
Small basins around trees and shrubs can capture runoff and put it to use, a common desert water-harvesting approach.

Step 4: Get trees ready

Trees fall in monsoon storms for a few repeat reasons:

Shallow roots. Trees watered lightly and often grow roots near the surface and can tip over in saturated soil and wind. Deep, less frequent watering encourages deeper roots.
Over-thinning. Stripping a tree's inner branches and leaving foliage at the tips, sometimes called lion-tailing, puts weight at the ends and makes limbs more likely to break. Moderate, structural pruning is better.
Dense, top-heavy canopies on fast-growing trees can act like sails. A qualified arborist can reduce weight without over-thinning.
Staking left too long or tied too tight can weaken young trees. Stakes should be removed once the tree can stand on its own.

Plan pruning well before storm season. Avoid heavy pruning in the heat of summer, when bark exposed to sun can burn. For large trees or trees near power lines, use a tree service with the right equipment and insurance.

Step 5: Set irrigation for the season

Monsoon rain is spotty. Your yard can get an inch while the next neighborhood stays dry. After a soaking storm, pause irrigation until the soil dries. A rain sensor or weather-based smart controller will do this automatically. EPA's WaterSense program labels controllers that meet efficiency criteria. Check for heads and drip lines displaced by runoff after big storms.

Step 6: Clear and secure

Clear leaves and debris from drains, channels and wall openings.
Secure patio furniture, umbrellas, shade sails and trash cans before storms.
Check that pool and yard drains move water away from the house.
Keep an eye on dead branches and palm fronds that can drop in wind.

Homes near washes and in the foothills

Homes near natural washes, especially in north Phoenix, north Scottsdale, north Peoria and other foothill areas, can see fast-moving water during storms. Never build walls or fill in a wash, and don't assume you can grade in one. Parts of north Scottsdale fall under the city's Environmentally Sensitive Lands overlay, and natural area open space easements there don't allow grading, clearing or structures. Check with your city or the county flood control district before work near a wash or in a floodplain.

After a storm

Stay away from downed power lines and contact your electric utility.
Walk the yard and note where water went, what washed out and what pooled. Photos are useful for a contractor.
Check walls, patios and footings for undermining.
Look for split limbs or leaning trees, and call a tree service for anything large.
Reset irrigation once the soil dries.

Before digging any fixes

Arizona's Blue Stake law requires notifying Arizona 811 at least two full working days before digging so underground utilities can be marked. Drain lines, channels and regrading often cross gas, electric and irrigation lines.

What affects the cost of drainage fixes

Costs depend on the length of channel or pipe, how far water must travel to a suitable outlet, access, how much rock and soil must be moved, whether caliche must be broken, and how much landscape must be restored. Get written estimates from more than one company and ask each to explain where the water will go.

Bottom line

A yard that handles monsoon storms has water going where it should, rock that stays put, and trees with deep roots and sensible pruning. If storms have already caused problems, request a drainage company and include photos. Read more about yard drainage and erosion control in the Phoenix area.

Frequently asked questions

When is monsoon season in Phoenix?

The National Weather Service treats roughly mid-June through September as Arizona's monsoon season. Storm activity varies a lot from year to year and neighborhood to neighborhood.

Why did my tree fall over in a monsoon storm?

Common causes are shallow roots from frequent light watering, over-thinned or top-heavy canopies, and saturated soil. Deep watering and moderate structural pruning help reduce the risk.

Can I build a wall across a wash on my property?

Generally you shouldn't without approval. Washes carry storm water, and work in them can require city or county review. In parts of Scottsdale, natural area open space easements prohibit structures and grading.

Sources and further reading

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