Most Tempe homeowners remember the morning of the September 2014 storm, even if they cannot name the date. Freeways sat underwater. Cars were stranded on the I-10. Rain fell at a pace the Valley almost never sees, and it fell on ground that could not take it. By the time the sun came out, Maricopa County was under a state of emergency.
That storm was labeled a 100-year event — a once-a-century kind of rainfall. The trouble is that a 100-year storm is a probability, not a promise, and the Valley has seen serious monsoon flooding in the years since. This post looks back at what September 2014 exposed, and what it still teaches about your home’s real risk.
Key Takeaways
- September 2014 flooded Valley freeways and homes and put Maricopa County under a state of emergency — a real 100-year-plus storm.
- A 100-year storm is a one-percent-per-year probability, not a once-a-century guarantee; the risk returns every monsoon.
- The homes that flooded worst had ordinary weak points: low lots, worn garage seals, and drains clogged with haboob dust.
- Storm runoff is usually contaminated and needs professional extraction, not a shop vacuum.
- Mold can start within 24 to 48 hours, so a fast, verified dry-out matters as much as removing the water.
What actually happened that morning
The remnants of a Pacific tropical system stalled over the Valley overnight and unloaded record rainfall in a matter of hours. Storm drains built for a normal monsoon cell were overwhelmed almost immediately. Water had nowhere to go but sideways — across streets, down driveways, and into homes.
Freeways became the most visible casualty. Stretches of interstate turned into standing lakes, cars were stranded, and crews closed lanes across the metro. Away from the cameras, homes across the Valley took on water, from Laveen to the East Valley. A state of emergency was declared for the county. For a day, one of the country’s largest metros was reminded how quickly desert drainage runs out of room.
Why the Valley floods so fast
It is tempting to file September 2014 under freak weather and move on. That is the wrong lesson. The Valley floods fast for reasons that have not changed: sun-baked soil that sheds water instead of absorbing it, a flat basin that pools runoff at every low point, and drainage sized for typical storms rather than record ones.
Add slab-on-grade homes, where the finished floor sits just inches above grade, and you have a region where an unusual rain does unusual damage quickly. The storm was rare. The vulnerability it found was ordinary, and it is still there.
- Desert hardpan sheds a fast inch of rain rather than soaking it up.
- The Valley’s flat basin sends runoff to the lowest lots and streets.
- Storm drains are built for common cells, not 100-year totals.
- Slab-on-grade floors give rising water a short trip indoors.
Active water emergency right now?
We answer 24/7 — a real person, not a machine.
The 100-year label fools people
A "100-year storm" does not mean one storm per century. It means a storm with roughly a one-percent chance of happening in any given year. You can get two in a decade. You can get one the year after the last. The label describes odds, not a waiting period, and treating it as a schedule is how people end up unprepared.
The honest takeaway from 2014 is not that you dodged your turn. It is that a rain capable of overwhelming the Valley’s drainage is on the table every single monsoon. Plan for the storm that can happen, not the average one that usually does.
What the flooded homes had in common
After a storm like that, patterns show up fast in the homes that flood worst. Low-lying lots and downhill driveways collected the whole block’s runoff. Garages with worn weather seals let water in at the bottom. Roof scuppers and area drains packed with dust — courtesy of the haboob that usually leads the rain — backed up and sent water where it did not belong.
None of those are exotic problems. They are the ordinary weak points of ordinary Valley homes, and every one of them is something you can check and fix on a calm spring afternoon.
- Sandbag or regrade where the yard and driveway slope toward the house.
- Replace worn garage-door bottom seals before the season.
- Clear roof scuppers and area drains of haboob dust and grit.
- Know where your low points are — and where the water will go.
Why fast water needs a fast, verified dry-out
Storm water is rarely clean water. Runoff picks up whatever is on the street — oil, fertilizer, sewage from an overwhelmed system — which pushes it into a contaminated category that a mop and a rented fan cannot handle safely. It has to be extracted, the structure has to be dried to a standard, and affected materials often have to go. Carpet pad, the paper facing on wet drywall, and soaked insulation rarely come back, and trying to save them is how a small job turns into a large one.
In our heat, the clock is short. Mold can begin within 24 to 48 hours of water sitting in a wall or under a floor. We run truck-mounted extraction, set LGR dehumidifiers and air movers, and verify the structure is dry with moisture meters and thermal imaging, following the IICRC S500 standard — not guessing from how the surface looks.
The twenty minutes before a big storm
September 2014 arrived on a forecast plenty of people saw and few acted on. When a major storm is a day or two out, there is still time for a short-notice pass — different from your spring prep, faster, and aimed squarely at the storm about to hit.
It takes about twenty minutes and targets the exact ways water got into homes that morning: blocked drains, worn door seals, and belongings sitting on the floor in the rooms most likely to flood. None of it is heroic. It is the difference, over and over, between the homes on a street that flooded and the ones that did not.
- Clear the roof scuppers and area drains once more — a haboob may lead the storm.
- Set sandbags or rolled towels at the garage door and the lowest exterior door.
- Move boxes and valuables off garage and closet floors.
- Confirm where your main water shutoff is, in case a pipe fails mid-storm.
- Charge phones and park vehicles on high ground, away from washes and dips.
Before the next one
The next storm with September 2014’s punch will not send a calendar invite. The homes that come through it best are the ones prepared during the quiet months — drains cleared, seals replaced, shutoffs tagged, contents lifted off the floor. None of it is expensive. All of it is easier in May than in the dark during a downpour.
If a storm does get water into your home, the smartest move is a fast call. We serve Tempe and the wider Maricopa County area, answer 24/7, and target a 60-minute response. The sooner extraction starts, the smaller the loss ends up being.
Frequently Asked Questions
Was the September 2014 storm really a 100-year event?
It was classified as a 100-year-plus storm — rainfall with about a one-percent chance in any given year. It brought record rain, flooded freeways and homes across the Valley, and led to a county-wide state of emergency.
Could a storm like that happen again soon?
Yes. The 100-year label is a probability, not a countdown. A comparable storm is possible in any monsoon season, which is why spring preparation matters every year rather than once a century.
Is monsoon flood damage covered by homeowners insurance?
Rising storm water usually is not — that typically requires separate flood insurance. Sudden internal failures, like a burst pipe during a storm, are often covered. We help document the loss so the correct coverage can be applied.
The water receded on its own. Do I still need help?
Almost certainly. Surface water leaving does not mean the structure is dry — moisture wicks into walls and subfloor and feeds mold within a day or two. A moisture-meter check confirms whether you have a real problem hiding behind the drywall.
