October 2026 Phoenix Storms & Flat Roofs

Event 1 — October 20–22: supercells with large hail and damaging winds

A potent low off the West Coast pushed a moisture plume north; precipitable water passed 250% of normal, a late-October record. Two supercells matter for Valley roofs:

When	Where	What fell	Damage NWS recorded
Tue Oct 20, evening	Chandler → Mesa (formed near Maricopa)	Hail 1–2 in	25–30 trees uprooted at a Chandler park; large trees down at a Mesa church; carports and vehicles damaged at a Mesa apartment complex
Wed Oct 21, afternoon	South of Avondale → Estrella foothills → Central Phoenix, Glendale, Metrocenter / I-17	Hail up to 2 in, "potentially locally larger"; winds over 60 mph	Numerous large trees uprooted; dented vehicles, shattered auto glass, broken residential windows

Statewide: 158 severe-thunderstorm warnings, 16 tornado warnings, 11 flash-flood warnings, three EF-1 tornadoes in the high country, and Arizona's first Tornado Watch since October 2010. Source: NWS Phoenix event summary.

What 2-inch hail does to a foam roof

Fresh, thick coating (20–30 mils, under 3 years old): usually nothing. The elastomer absorbs the hit.
Chalked coating (5+ years, rubs white): white crush marks, star cracks, flakes in the scuppers. Each crack is a path for the next rain. This is a spot-coat job if it is dozens of hits, a recoat if it is hundreds.
Existing blisters: hail splits them. A split blister is open foam — cut out and refoam, a few hundred dollars each. See blisters and bubbles.
Wind over 60 mph: lifts coating at parapet edges and around AC curbs, and drops limbs that puncture. Check edges and anything that was on the roof.

If your roof is in the Chandler/Mesa or Central Phoenix/Glendale paths and the coating was due, assume hits and walk it. Hail is a covered peril on most policies; a chalked coating is not — the dated photos decide which story the adjuster hears.

Event 2 — October 30 – November 1: the Halloween-weekend rain

A cut-off low brought steady rain rather than cells. NWS Phoenix forecast an average ½–¾ in on Friday with more under storms, a lull on Halloween, and 1–2 in across the metro on Sunday (2–3 in in the high terrain) with a flood watch for central Arizona and hail of ½–1 in in spots. Sky Harbor had recorded measurable rain on October 31 only nine times in 130 years, last in 1987. Going in, the airport had 3.20 in for the year — 45% below the 5.87 in normal.

Measured so far (as of Sunday afternoon, November 1 — the event is still in progress):

Gauge / area	Total	Window	Source
Scottsdale (Flood Control District gauge)	4.25 in	through 8 AM Sunday	FCD gauge, as reported by local meteorologists
Scottsdale, west of Gainey Ranch	nearly 3 in	Friday alone	FCD gauge via KJZZ
Wittmann	3.43 in	through 8 AM Sunday	FCD gauge, as reported
Cave Creek	2.83 in	through 8 AM Sunday	FCD gauge, as reported (large hail Friday)
Apache Junction	2.09 in	through 8 AM Sunday	FCD gauge, as reported
NE Maricopa / Four Peaks – Saguaro Lake	0.5–1.25 in	Sunday morning, by 9:10 AM	NWS flash-flood warning
Phoenix Sky Harbor	≈0.4 in Friday–Saturday; Sunday still accumulating	year-to-date 3.20 → 3.62 in by Sunday morning	NWS climate record via ABC15

Friday, October 30: the NWS described cells "dumping more than an inch of rain in under an hour in several areas." Scottsdale took the worst of it — six people rescued from stalled cars at Stanford Drive / 32nd Street in Phoenix, more pulled from a wash at Hayden Road and McCormick Parkway, Shea Boulevard closed between 65th and 70th Streets for downed power lines, standing water at Scottsdale Road and Deer Valley Road, flooding on Doubletree Ranch Road in Paradise Valley and across Apache Junction. More than 5,000 SRP/APS customers lost power; about 4,000 were still out Sunday morning. Large hail hit Cave Creek and Anthem. Central Phoenix and Glendale saw lighter, steadier rain.
Sunday, November 1: flash-flood warnings for Maricopa and Gila counties from about 7:30 AM through early afternoon; another 1–2 in forecast for the Valley through the day with afternoon storms gusting 30–40 mph. Halloween 2026 was the first measurable-rain Halloween at Sky Harbor since 1987.
Rain ends Monday morning, November 2, with a dry first week of November behind it — which is exactly when ceiling stains from this weekend start showing.

The Sky Harbor number understates the metro: the airport sat under the lighter central band while the north and east Valley gauges caught 2–4 in. Official event totals (NWS Sky Harbor climate report; Flood Control District of Maricopa County gauges for Phoenix, Mesa, Scottsdale, Glendale, Chandler, Gilbert and Tempe) will be added once the weekend is posted.

What an inch or two of slow rain does to a foam roof

It finds the hail damage. Every crack from October 21 that was dry for a week is now a wet path. First leaks show up as ceiling stains 24–72 hours after the rain stops.
It tests the drains. Dust from a dry year plus leaf fall plugs scuppers. Water still on the roof at 48 hours is ponding; on an acrylic coating that is where the softening starts.
It shows the low spots. Photograph where the water sits on Tuesday; that is the map for a tapered-foam fix later.

The checklist for both events

Tuesday Nov 3 (48 hours after the rain ends): scuppers running? standing water? ceiling stains?
Walk the roof once dry: white hail marks, split blisters, flakes in scuppers, lifted edges.
Photograph everything with the date before any tarp or patch.
Hail hits on a chalked roof in the two supercell paths: call the insurer and the roofer; get the written cause-of-damage note.
Standing water and no hail: clear drains, then book the repair or the recoat the calculator says is due.

The 30-second chalk test

Rub a dark cloth or your palm firmly across the coating in direct sun.

Tap a result.

Sources: NWS Phoenix event summary for October 20–22, 2026; NWS Phoenix forecast quoted by KTAR (Oct 29, 2026); NWS daily climate report for Phoenix Sky Harbor via Iowa Environmental Mesonet. Photos on this page, when added, will be the contractor's own or credited public-domain NWS/NOAA imagery — not news-station images.

Questions people ask

Did the October 2026 hail storm damage foam roofs in Phoenix?

Where the coating was chalked or thin, yes — 1–2 inch hail cracks a tired top coat and splits old blisters. The supercell paths were Chandler/Mesa on October 20 and south-of-Avondale through Central Phoenix and Glendale on October 21 (NWS). A fresh coating generally took it without damage.

How much rain fell in Phoenix over Halloween weekend 2026?

NWS forecast ½–¾ in on Friday and 1–2 in on Sunday across the metro, with 2–3 in in the high terrain. Measured totals are added to this page from the Sky Harbor climate report once posted; before the weekend the airport stood at 3.20 in for the year, 45% below normal.

Should I file an insurance claim for hail on a foam roof?

If there are hail marks and the roof is in one of the supercell paths, document it (dated photos, roofer's written note) and ask the insurer. Hail is a sudden, covered peril on most policies; a worn coating is maintenance and is not.

When is the next storm risk for Phoenix roofs?

Monsoon season is June 15 – September 30; outside it, cut-off lows like the Halloween system bring slow rain a few times each winter. The storm watch page logs each NWS event as it happens.

October 2026 storm review: hail, wind and a wet Halloween