Colorado Hail Storm Report, July 28, 2026: Castle Rock and Lyons
August 16, 2026
By Red Hawk Roofing
A hail-producing storm crossed Colorado on July 28, 2026. The National Weather Service logged 3 hail reports inside Red Hawk’s service area that day, the largest at 1.00 inches. Castle Rock and Lyons took the most reports.
The Colorado hail map — July 28, 2026
Every hail report in Red Hawk’s service area
These are National Weather Service Local Storm Reports — hail an observer found on the ground, not a radar estimate. Times are MDT.
| Location | Size | Time | Source |
|---|---|---|---|
| Lyons | 1.00" | 2:04 PM | CoCoRaHS |
| 3 NW Castle Rock | 1.00" | 2:16 PM | Public |
| 3 NW Castle Rock | 0.75" | 2:14 PM | Public |
By city: Castle Rock 2 reports, Lyons 1 report. A hail report always names the largest stone an observer found, not the average size that fell across every roof.
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Why 1.00-inch hail matters to an asphalt roof
Damage scales hard with stone size. A one-inch stone falls at about 41 mph and lands with roughly 1.3 joules of energy. A 1.75 inch stone falls at about 65 mph and lands with roughly 16 joules — about thirteen times the impact. Denver-area elevation adds another 8 to 10 percent to fall speed.
Published impact studies put the onset of functional damage near 1.00 inch for three-tab asphalt shingles, 1.25 inches for architectural shingles, and 2.00 inches for Class 4 impact-rated products. The largest report on this day was 1.00 inches, at or near the threshold for three-tab shingles.
The damage usually is not visible from the ground. Hail bruises the shingle — fracturing the mat beneath a surface that still looks intact — and the bruised area then sheds its protective granules over the following months. A roof hit in June can look fine all summer and start leaking by winter.
Radar-estimated hail is not measured hail
Radar hail algorithms output a deliberate high-end estimate of what may exist inside a storm cloud, not a measurement of what landed on your roof. Radar estimates characteristically run above what observers actually recover. Treat the shaded swath on the map as the search area and the ground reports as the confirmed observations. If a contractor tells you radar showed three-inch hail at your address, ask whether anyone measured it.
What to do if you were under it
- Check from the ground, not the roof. Walking a hail-struck roof is how people get hurt.
- Look in your gutters. Granules washing off in quantity is the most common early sign.
- Check soft metal. Roof vents, gutters, flashing, the mailbox, AC condenser fins. Dents in soft metal date the storm.
- Photograph what you find with your phone. Phone photos carry a timestamp. Do not edit them.
- Get it inspected. Especially if this storm was months ago — that is exactly when bruising starts to surface.
Radar estimate and ground reports by city — July 28, 2026
The map above is the search area. This table asks two narrower questions for each Red Hawk service-area city: did any NWS ground report come from inside the city’s actual boundary, whatever locality name the NWS filed it under; and did a radar-estimated hail band of 1.00 inch or larger cross that boundary? A ground report is an observation and always lists the city. The band is an MRMS estimate, not a measurement.
| City | Radar estimate | Share of the city under it | Ground reports inside it | Boundary used |
|---|---|---|---|---|
| Lyons | 1.50" est. | 2% (northwest part) | 1 report, 1.00″ (measured) | city limits |
| The Pinery | 1.00" est. | 14% (west part) | none | city limits |
| Castle Rock | 0.50" est. | 13% (north part) | 2 reports, largest 1.00″ (reported) | city limits |
Radar estimated hail to 1.50 inches over part of Lyons (about 2 percent of it, in its northwest part); the 1.00 inch band covered about 55 percent of it. On the ground, one National Weather Service hail report came from inside the Lyons city limits: 1.00 inch (measured).
Radar estimated hail to 1.00 inch over part of The Pinery (about 14 percent of it, in its west part). No ground observer reported from The Pinery that day — reports come from where people happen to be, and their absence is not evidence that nothing fell.
On the ground, two National Weather Service hail reports came from inside the Castle Rock city limits, the largest 1.00 inch (reported). Radar placed only the 0.50 inch band over part of Castle Rock (about 13 percent of it, in its north part), an estimate below the size reported on the ground.
The strongest radar-estimated core of this storm, the 2.00 inch band (the largest of two separate cores at that band), crossed no Red Hawk service-area city. It sits over unincorporated Boulder County, ZIP code 80540, about 1.5 miles west of the Lyons city limit. Named roads under it: North Saint Vrain Drive, US Highway 36 and Colard Lane. The nearest ground report was 2.2 miles away (“Lyons”, 1.00 inch). No ground observer reported from inside it — reports come from where people happen to be, and their absence is not evidence that nothing fell.
City boundaries are the U.S. Census Bureau TIGER/Line 2025 place limits; Denver neighborhoods use the City and County of Denver’s statistical neighborhood polygons. A city is listed if any NWS ground report came from inside that boundary, or if a 1.00 inch or larger radar band crosses it; a ground report is never left off for the size of the radar estimate. The 0.50 inch band also crossed 14 other service-area cities with no ground report inside them; those are not listed because hail under one inch rarely damages asphalt shingles and a radar band that small is an estimate below that threshold. A band at or above 1.00 inch also clipped the edge of 2 further service-area cities without a ground report inside them, by less than one radar grid cell of area. Those are not listed: MRMS is gridded at about one kilometre and the swath it draws is displaced from where the stones landed, so an overlap that small does not establish that hail fell in the city. Bands over cities more than 10 miles from this storm’s own reports belong to other storms on the same day and are not listed here.
Hail duration, warnings and wind
The same system produced 26 Colorado wind reports that day, the strongest 70 mph at 1 SSW Bennett. Wind damage and hail damage look different on a roof and are assessed separately.
CoCoRaHS volunteer observers logged 4 Colorado hail observations on this date, the longest running 12 minutes at South Fork 0.6 S. That network records how long hail fell and what it damaged, which NWS storm reports do not capture.
Frequently asked questions
Was there hail in Castle Rock on July 28, 2026?
Yes. The National Weather Service logged 2 hail reports in the Castle Rock area on July 28, 2026. Across Red Hawk's service area there were 3 reports that day, topping out at 1.00 inches.
How big was the hail on July 28, 2026 in Colorado?
The largest hail reported inside Red Hawk's service area was 1.00 inches. Remember that a hail report names the largest stone found, not what fell across a whole neighborhood.
Which Colorado towns had hail on July 28, 2026?
Reports came in from Castle Rock, Lyons.
Could my roof still have damage from this storm?
Yes. Hail bruising fractures the shingle mat beneath a surface that still looks intact, and the bruised area sheds granules over the following months. Damage from a storm earlier in the season is often only becoming visible now, which is exactly why it is worth checking.
How do I check my roof for hail damage?
From the ground, never by climbing up. Look for granules collecting in gutters and at downspout outlets, and dents in soft metal such as roof vents, gutters, flashing, the mailbox and AC condenser fins. Soft-metal dents matter most because they date the storm.
Were there damaging winds in Colorado on July 28, 2026?
Yes. The National Weather Service logged 26 wind reports in Colorado on July 28, 2026, the strongest 70 mph at 1 SSW Bennett. Wind and hail damage a roof differently — wind lifts and creases shingles along edges and ridges, hail bruises the field.
How long did hail fall in Colorado on July 28, 2026?
CoCoRaHS volunteer observers — a trained precipitation network separate from NWS storm spotters — logged 4 hail observations in Colorado on July 28, 2026. The longest was 12 minutes at South Fork 0.6 S. CoCoRaHS reports carry duration and damage notes that an NWS report does not.
Was there hail in Lyons on July 28, 2026?
Radar estimated hail to 1.50 inches over part of Lyons (about 2 percent of it, in its northwest part); the 1.00 inch band covered about 55 percent of it. On the ground, one National Weather Service hail report came from inside the Lyons city limits: 1.00 inch (measured).
Was there hail in The Pinery on July 28, 2026?
Radar estimated hail to 1.00 inch over part of The Pinery (about 14 percent of it, in its west part). No ground observer reported from The Pinery that day — reports come from where people happen to be, and their absence is not evidence that nothing fell.
Red Hawk tracks every hail day across the Front Range. See our other storm reports for the rest of the 2026 season.
City-by-city reports and hail histories
Not sure what to look for? Start with what hail damage looks like on a roof and the Colorado hail claim guide.
Red Hawk works Colorado roofs year round. We'll still be here next season.
Schedule My Free Inspectionor call (720) 771-8921
Storm figures are National Weather Service Local Storm Reports for Colorado on July 28, 2026, retrieved from the Iowa Environmental Mesonet archive and de-duplicated. Radar swath analysis by ExoVzn, an independent forensic meteorology firm, using NOAA MRMS data. Impact-energy and damage-threshold figures are from published hail impact research. Storm reports indicate where hail occurred; only a physical inspection establishes whether a specific roof was damaged.