Local Irvine & Orange County · 5 min read
Irvine Gets ~13 Inches of Rain — Almost All of It November to March. Is Your Home Ready?
Eight dry months silt up every drain you own. Then the whole year's rain arrives in a handful of storms. October is the month to fix that.
Short answer
Irvine takes about fourteen inches of rain a year and nearly all of it falls between November and March, frequently in a handful of intense storms. Preparation is drainage first — clear every area drain, downspout and subdrain outlet — then grade, roof, gutters and the garage threshold. October is the month to do it.
Irvine averages about fourteen inches of rain a year, and almost all of it falls between November and March — increasingly delivered by atmospheric-river events that drop several inches in a day or two.
That pattern is what causes the damage. Eight months of dry weather silts up every drain on your property and degrades every sealant on your roof. Then the whole year's water shows up at once and finds all of it simultaneously.
Drainage: The Highest-Value Hour You Will Spend
Every area drain, yard drain and channel drain on your property accumulates silt, leaf litter and landscaping debris over the dry months. Many are also progressively covered by planting as beds mature.
Find them all — walk the perimeter, check side yards, planters, patios and any low point. Clear each one and run a hose into it to confirm it flows.
If you cannot find a drain you know exists, or if nothing has ever come out of a subdrain outlet at the toe of a slope or through a retaining wall, that is worth investigating before November rather than during a storm.
Grade: The Problem Nobody Notices Happening
Soil should slope away from your house. Over twenty or thirty years of adding mulch, refreshing planter beds and installing new landscaping, the finished grade quietly rises — and in a great many older Irvine homes it now sits above the slab edge.
When that happens, water arriving at the wall has a downhill path into the house rather than away from it. It is the single most common storm intrusion condition we find, and it has nothing to do with the building.
Walk the perimeter with a level or just your eyes. Anywhere planter soil is at or above the slab, dig it back down. Cheap, permanent, and it fixes a recurring problem.
Standing water right now? Call us before you do anything else.
We are on site within 60 minutes anywhere in Irvine, 24 hours a day.
The Roof, From the Ground
Most Irvine roofs are concrete or clay tile, and the tile is a shedding layer rather than the waterproofing. The underlayment beneath it is what keeps water out, and on 1970s and 1980s homes that underlayment is frequently at or past service life even where the tile looks perfect from the street.
From the ground with binoculars: cracked or slipped tiles, shifted or missing ridge caps, debris in valleys, and the rubber boots around plumbing vents — those have an eight-to-twelve-year life in this UV and they are a very common leak source.
Do this after the first significant Santa Ana event of the season and photograph anything you find with the date. That photograph is what turns a January ceiling leak into a covered storm claim.
Gutters and Downspouts
Clear the gutters. A blocked gutter overflows down the wall and behind the stucco rather than into the downspout, which puts water into the wall assembly instead of onto the ground.
Confirm every downspout actually discharges away from the foundation. A downspout dumping at the base of a wall is the same as no downspout at all.
Extensions or splash blocks routing water four to six feet out are inexpensive and effective. Underground drain lines from downspouts should be checked for blockage too — those silt up like everything else.
The Driveway and the Garage Threshold
If your driveway pitches toward the garage rather than the street, storm runoff has a direct path under the door. This is the most common storm entry point we see in Irvine, and it is entirely a grading and detailing issue.
A trench drain across the driveway apron, or a threshold seal on the garage door, solves it permanently. Both are modest projects and both end a problem that otherwise recurs every wet winter.
Meanwhile, do not store anything you care about directly on a garage floor. Pallets, shelving or plastic bins with lids — anything that keeps cardboard off the slab.
The Rest of the October List
Trim tree limbs away from the roof and away from the house. Wind-driven limbs are a leading cause of tile damage and they arrive in the same season.
Check window and slider weep holes at the bottom of the frames — these clog with dirt and cause water to back up into the wall instead of draining out.
Test your sump if you have one, which in Irvine mostly applies to subterranean parking and some commercial properties.
And if you are going to buy flood insurance, buy it now. NFIP policies generally carry a 30-day waiting period, which makes October the last reasonable month to decide.
From the field
Grade: the problem nobody notices happening
Of everything on an October list, the item most homeowners have never checked is the grade against the foundation. Soil should fall away from the house — the rule of thumb is roughly six inches of drop over the first ten feet. What actually happens over twenty years is that mulch gets topped up every spring, planters get built, a patio gets poured, and the grade quietly reverses until the ground beside the wall is higher than the slab.
That is invisible until a storm, and then it is the whole problem: water pools against the foundation and finds the cold joint, a penetration or a weep. Homeowners describe it as the house leaking. It is the ground delivering water to a wall that was never designed to sit in it. The fix is usually removing accumulated material rather than adding anything, which makes it one of the few genuinely free repairs on the list.
The honest tradeoff on drainage work: clearing drains and correcting grade is a Saturday and costs nothing but time. Installing new drainage — French drains, additional area drains, a regraded swale — is real money and it is occasionally the right answer on a lot that genuinely cannot shed water. Do the free things first and see what a real storm does, because a surprising number of properties are fixed by a bucket of leaves and a wheelbarrow of mulch removed.
Find your subdrain outlets before November
On a graded pad they discharge at the toe of a slope or through a retaining wall. If you cannot find yours, or it has never discharged, that is worth investigating in October.
Efflorescence is evidence, not cosmetics
Chalky white mineral bloom on a retaining wall or stucco means water is passing through that assembly. It is the cheapest early warning you will get.
Frequently Asked Questions
When is Irvine's rainy season?
November through March, with the great majority of the annual total falling in that window. The city averages about fourteen inches a year, increasingly delivered in concentrated atmospheric-river events rather than spread across the season. That concentration is what stresses drainage systems.
What is the most important storm prep item?
Clearing every area drain on the property, and checking that finished grade still slopes away from the house. Those two conditions — blocked drains and grade raised above the slab edge by decades of added planter soil — account for a large share of the storm intrusion we respond to, and both are a weekend of work.
Should I get flood insurance in Irvine?
It is worth pricing, particularly if you are at the bottom of a grade, near a channel, or have a driveway pitched toward your garage. Standard homeowners policies exclude flood entirely, and NFIP policies carry a 30-day waiting period — so the decision has to be made before the season, not during a storm.
Need help with this in Irvine?
We handle this work every week across Irvine and Orange County. A live dispatcher answers 24/7, gives you an arrival window, and tells you what to do while you wait. Free on-site assessment and written scope before any demolition.
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