What happened at Denver International Airport on July 13, 2011?

Hail up to golf ball size, very heavy rain and gusts to 59 mph damaged 40 planes and 83 cars in the airport lots, stranded about 1,500 passengers overnight and led to at least 220 cancelled flights over the following days. NOAA puts the aircraft damage alone at nearly $5 million.

How big was the hail in Watkins?

4.5 inches, about the size of a grapefruit. NOAA reports that softball-size stones cratered the north sides of mobile homes in a Watkins park of 52 mobile homes, 14 RVs and 3 houses, and that as many as 200 residents were left homeless.

Was west Denver badly hit on July 13, 2011?

West Denver, Lakewood and Sheridan had quarter to ping pong ball hail early in the evening, with significant tree damage southwest of downtown. That size can bruise older shingles, but the most severe hail that night fell east of the metro.

July 13, 2011 Denver Hail: Lakewood, DIA and Watkins

The July 13, 2011 Denver hailstorm was really a string of storms across one evening. Between about 6:05 and 9:40 p.m., NOAA logged hail from Lakewood and west Denver to Lyons, Buffalo Creek and Denver International Airport, and the largest stone, 4.5 inches (grapefruit), fell on Watkins east of the metro. NCEI’s record for the storm is $164.8 million across the Urban Corridor, including 40 damaged planes at DIA and a Watkins mobile home park where up to 200 residents lost their homes.

What happened on July 13, 2011

The first reports came at about 6:05 p.m. south-southwest of Lakewood, with hail growing from penny to half dollar size in a few minutes. Through about 6:40 p.m. the storm crossed west and south Denver and Sheridan with 1 to 1.5 inch hail; the Storm Prediction Center’s log notes significant tree damage 1 mile southwest of downtown. Separate storms put quarter hail near Lyons and 2-inch hail at Buffalo Creek in the foothills by 7:30 p.m.

The worst came last. At about 9:30 p.m., gusts to 59 mph and hail up to golf ball size hit Denver International Airport. NWS Boulder’s summary says 40 planes were damaged, about 1,500 passengers were stranded overnight, and at least 220 flights were cancelled over the next several days as Frontier and United pulled dozens of planes for repairs. Ten minutes later, 4.5-inch hail fell on Watkins. Two people suffered minor injuries, 35 to 40 homes were damaged, power was cut to about 1,200 customers, and the Red Cross opened a shelter at Bennett High School. A tractor-trailer was flipped on Interstate 70 near Watkins Road.

Where the hail fell

Area	Largest hail on record	Size name
Watkins	4.50 in.	Grapefruit
Buffalo Creek	2.00 in.	Hen egg
Denver International Airport	Golf ball (NWS summary)	Golf ball
West and southwest Denver	1.50 in.	Ping pong ball
Lakewood	1.25 in.	Half dollar
Sheridan	1.25 in.	Half dollar
Lyons and south Denver	1.00 in.	Quarter

Insurance claims in the Watkins, Bennett and Brighton areas alone were estimated at $17 million, according to the NCEI record.

What hail this size does to a roof

The two ends of this storm need different checks. In Lakewood and west Denver, quarter to ping pong ball hail usually leaves granule loss and small bruises on shingles, which matter most on roofs that were already aging in 2011. Those marks are easy to miss and weather into something that looks like normal wear.

Grapefruit hail is a different category. NOAA describes it cratering the sides of mobile homes. On a house, stones that size punch through shingles and underlayment, break tile, smash skylights and dent or split siding. Thin metal roofs on manufactured homes and outbuildings can be holed outright. At that size, repair is rarely an option for roofs in the core of the storm.

How to check a roof for this storm

If you were in west Denver or Lakewood and your roof dates from before 2011, look for small, dark spots and missing granules on the slopes that faced the storm.
In the eastern plains communities, check siding and window wraps as well as the roof; this storm damaged walls as well as roofs.
Look at the attic decking for old water stains that line up with the hail date.
Book an inspection with photos. On a roof this old, the useful question is whether the remaining life justifies repair or calls for replacement.

Claim timing for a Colorado storm

Colorado sets no single deadline to report roof damage; your policy does, often as prompt notice. A Colorado homeowner's policy cannot give you less time to sue than the statute of limitations (C.R.S. 10-4-110.8(12)), and the Division of Insurance advises calling your insurer or agent soon after a hailstorm. Replacement cost policies usually hold back depreciation until the work is done: see finishing repairs to recover depreciation and how long you have to file a hail claim.

This storm is now 15 years old, and hail marks weather. An inspection shows whether marks look fresh or aged, which an adjuster weighs when tying damage to a date. General information, not legal advice; the claim is always yours, and our part is the inspection, dated photos and written scope.

Denver, CO inspection and hail help

If you live in the Denver metro, start with our Denver hail damage repair page, book a free Denver roof inspection, or read what a Denver roof inspection covers. Integrity Roofing and Painting is veteran-owned and family-run since 1990, an Owens Corning Platinum Preferred contractor with 650+ Google reviews, and we respond the same business day. Call (303) 209-0152.

Other recorded storms in the Denver metro

Sources: NOAA SPC storm reports, July 13, 2011; NOAA NCEI Storm Events Database, event 331553 (Watkins, 4.50 in., $164.8 million); NOAA NCEI Storm Events Database, event 320139 (near DIA, 51 kt gust); NWS hail size reference; C.R.S. 10-4-110.8 (unofficial reproduction); Colorado Division of Insurance, hail consumer advisory (May 22, 2024).

The July 13, 2011 Denver Hailstorm, From Lakewood to Watkins