Colorado's Labor Day Week Hail (Aug 31–Sep 7, 2026): 3.94-Inch Hail on the Plains

I've been roofing on the Front Range for about three years, and Labor Day is usually when Colorado homeowners quietly file hail season away for the year. This year the radar kept going. Between August 31 and September 7, NOAA's MRMS network estimated hail somewhere in Colorado on four separate days, with radar estimates reaching 3.94 inches — one of the largest single readings of the 2026 season, though not the year's biggest.

But the honest headline isn't the size. It's the geography. The severe hail this week stayed on the plains. If you live in Denver, Aurora, or the south metro, the storm that produced that 3.94-inch reading was nowhere near your roof.

Here's what the data actually shows, what it doesn't, and what I'd tell a homeowner to do about it.

What the Radar Recorded, Day by Day

MRMS (Multi-Radar Multi-Sensor) is a NOAA system that stitches several weather radars together and flags grid cells — each roughly one square kilometer — where it estimates hail is falling. It is a model estimate, not a physical measurement, but it is the most consistent address-level record we have of which neighborhoods sat under a storm.

The counts below are distinct grid cells estimated at 1 inch or larger. MRMS re-snapshots the same cell many times a day; each cell is counted once here, however often it was re-reported. The size column is the peak among each day's new cells — not the peak sitting in its 24-hour bucket, which can be yesterday's stone. That distinction is why September 6 reads 1.60 inches here and on its own storm page, even though 2.72 inches is still inside its bucket from the day before.

Four new hail days inside the Aug 31–Sep 7 window. For a week that starts with Labor Day, that is a working storm week, not a season winding down.

Why September 1 Doesn't Count as a Hail Day

This is the part most storm coverage gets wrong, so it's worth being precise.

MRMS publishes a trailing 24-hour maximum. A snapshot taken just after midnight re-reports the previous day's cells under the new date. So a date can show hundreds of flagged cells and still be, in the strict sense, the same hail that fell the day before.

That is exactly what September 1 is. All 527 of its cells had already been reported on August 31 — not one new cell, and the identical 3.94-inch peak. September 8 is the same kind of repeat of September 7. Colorado's season counter on the Colorado hail statistics page excludes both dates for that reason, and so does this post.

If you see a roundup this week claiming Colorado had five or six hail days over Labor Day week, or claiming September 1 was the biggest day of the week, that's the trailing-maximum artifact being read as a second storm.

Where It Actually Hit: the Plains, Not the Metro

The 3.94-inch core on August 31 sat near 37.57°N, 103.77°W — southeastern Colorado, out toward the Las Animas and Baca county country. It was a real, well-formed core, not a radar artifact: the surrounding grid decays smoothly outward (3.94 / 3.63 / 3.11 / 3.07 inches), with 62 neighboring cells at an inch or more.

It also fell over some of the emptiest country in the state, which is why you probably didn't hear about it.

Inside the Denver metro, the week looks completely different:

August 31 and September 5: no cells of 1 inch or larger in the metro at all. September 5's strongest cells sat in the far northeastern corner of the state, with a county storm record published for Weld County.

September 6: 44 cells, topping out at 1.20 inches. The day's larger readings were well north, in Larimer and Weld counties.

September 7: 116 cells, again topping out at 1.20 inches, with the day's stronger cells out east in Adams County.

So the two heaviest statewide days produced nothing measurable over the urban corridor, and the metro's own activity was a modest 1.2-inch clip on the back half of the week. Both things are true at once: this was a busy radar week for Colorado, and it was a quiet one for most Front Range roofs.

The South Metro on September 6

The one Front Range signature worth naming is small and I want to size it honestly. On September 6, MRMS put a tight three-cell cluster between Parker and Lone Tree — around 39.52°N, 104.83°W — estimated at 1.03, 1.11, and 1.20 inches, roughly 3 to 4 miles from both town centers.

That is three grid cells, not a swath. It is worth a look at your gutters if you're in that pocket; it is not the kind of footprint that puts a neighborhood into replacement season. Anyone knocking your door this week citing "the Labor Day storm" as a reason your roof needs replacing is describing a storm that, in the south metro, was about three square kilometers of marginal hail.

What 3.94 Inches Means on a Roof

At 3.94 inches you are past baseball and into softball territory. For context from the jobsite: around 1.5 inches (golf ball) asphalt shingles typically start bruising — the granule matrix compresses and fractures, and it isn't always visible from the ground. By 2 inches you're into more consistent bruising, cracked tab corners, and accelerated granule loss. Past 3 inches, an older asphalt roof under the core rarely comes through clean.

Two honest caveats on that number, though.

First, 3.94 inches was the single strongest cell in the state, not what fell on any particular street — and that cell was on the southeastern plains, hours from the metro. Second, MESH is tuned so that roughly 75% of measured hail comes in at or below the radar estimate; read a size as a class (within about one tier), not as a caliper reading.

And the thing I say on every one of these posts, because it stays true: HailScore™ measures hail exposure recorded in NOAA data. It does not confirm damage. Two houses on the same block can come out of the same storm completely differently. Only someone physically on your roof can tell you what your shingles actually look like.

The Class 4 Question Worth Asking Before Next Season

Every September I get the same question from homeowners who just watched a storm season go by: should the next roof be impact resistant?

Class 4 is the top tier of the UL 2218 impact rating — a laboratory test in which steel balls are dropped on a shingle from a set height. It measures how a product behaves under a standardized impact. It is not a guarantee that a Class 4 roof comes through a given storm undamaged, and no rating class promises that.

What it does reliably change is your premium. Most major carriers in hail-prone states discount the wind and hail portion of the policy for a UL 2218 Class 4 roof, and in Colorado that portion is a large share of the bill. If you're facing a roof replacement in the next year anyway, the upgrade math is worth running before you pick a product — the full breakdown, with per-square costs and payback periods, is in our impact resistant roof cost guide.

Ask your agent specifically what your carrier's Class 4 discount is and get the answer in writing before you commit to a shingle. I'm a roofer, not an insurance agent — but I've watched a lot of homeowners wish they'd asked that question a season earlier.

What to Do Before Hail Season Closes Out

1. Check the record for your address, not the headline for your city. A statewide roundup can't tell you whether a storm tracked over your street. Our free hail report by address pulls the documented storm history for a specific property — dates, estimated sizes, and distances — from 39.6M+ NOAA-linked hail records across all sources, including 8.7M+ NOAA NEXRAD radar records going back to 2015. No signup for the basic report.

2. Know your roof's age. A 15-year-old asphalt shingle and a 3-year-old one respond very differently to the same storm. If you don't have records, your county assessor's permit history is a reasonable starting point.

3. Walk the easy evidence first. Gutters, downspouts, window screens, and the fins on aluminum vents dent cleanly and are visible from the ground. They're a decent proxy for whether anything hit hard enough to matter.

4. Schedule an inspection if the record justifies it. A qualified roofer should be able to distinguish impact bruising from age-related granule loss, and should be willing to explain what they're seeing on your specific roof. Be skeptical of anyone who quotes a replacement from the driveway.

5. Document before anyone visits. Dated photos of the roof surface, gutters, and any vehicle damage give you a baseline that predates the first contractor or adjuster conversation.

Colorado is among the most hail-active states in the country, and this week's record shows the season isn't finished. But the useful version of that sentence is address-level, not statewide — and for most of the Front Range, this particular week was quieter than the raw numbers make it look.

For the storm week just before this one, see our August 24–28 Colorado hail recap, which tracked a considerably larger South Metro event.

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Look up your property's full hail exposure history, free, at HailScore. HailScore documents radar-recorded hail exposure near an address. It does not confirm roof damage — only a licensed inspector can do that.