The June 6, 2020 Denver derecho was a wind event, not a hailstorm: a fast line of thunderstorms that brought gusts of 70 to 81 mph to the metro on a Saturday afternoon. NOAA’s database lists 55 thunderstorm wind reports in the seven metro counties between about 12:40 and 5:45 p.m., with an 81 mph gust measured at Parker and 78 mph measured at Denver International Airport. Trees came down across Denver and Aurora, and more than 208,000 Xcel Energy customers lost power statewide.
What happened on June 6, 2020
NWS Boulder’s summary describes “a rare derecho; a large fast-moving complex of thunderstorms with powerful straight-line winds” that formed over the Great Basin, crossed the northern and central mountains by midday, and moved rapidly northeast across the I-25 corridor by mid-afternoon. Gusts of 60 to 80 mph were common along its path, a few topped 90 mph, and the highest, 110 mph, was measured at the Winter Park ski area at about 12,000 feet. A strong pressure gradient also produced 59 to 71 mph gusts before and after the line passed.
In the metro, the strongest winds came between about 3:45 and 5 p.m. Measured gusts reached 78 mph at Columbine at 3:44 p.m., at Denver International Airport at 4:01 p.m. and at Barr Lake at 4:04 p.m., and 81 mph at Parker at 4:52 p.m. The Storm Prediction Center’s preliminary log adds 80 mph near Castle Pines, 78 mph near Chatfield Reservoir and 76 mph at Centennial Airport. In Denver, a billboard fell onto a bakery and a falling tree seriously injured a man; a large tree was uprooted on Downing Street near Alameda Avenue.
Where the wind did damage
| Area | Strongest gust on record | Reported damage |
|---|---|---|
| Parker | 81 mph (measured) | Not described in the record |
| Denver | 81 mph (estimated) | Trees uprooted, 6 to 10 inch limbs snapped, billboard down |
| Aurora (Cherry Creek and Buckley) | 81 mph (estimated) | Trees snapped or uprooted |
| Centennial Airport area | 81 mph (estimated) | Numerous power poles and shallow-rooted trees down |
| Denver International Airport, Barr Lake and Columbine | 78 mph (measured) | Tree limbs snapped near Barr Lake |
| Northglenn | 70 mph (estimated) | Greenhouses and a gazebo overturned |
| Brighton | 75 mph (estimated) | Fence down, limbs up to 6 inches snapped, numerous trees damaged |
NOAA records thunderstorm wind in knots; the speeds above are converted to miles per hour.
What 70 to 80 mph wind does to a roof
Wind damages a roof from the edges in. Gusts get under the shingles along the eaves, rakes and ridge first, break the adhesive seal strips and fold the tabs back. Some shingles tear off; others crease and settle back in place, which is easy to miss from the ground. Ridge caps and hip shingles lift, and loose flashing, gutters and satellite mounts can pull free. Falling trees and limbs, which this storm brought down across the metro, puncture roofs and crack decking.
The wind rating on the shingle wrapper matters here. Shingles tested to ASTM D3161 Class F are rated for 110 mph, well above this storm’s gusts, but only when installed with the manufacturer’s nailing pattern and starter strips. A roof nailed too high or with old, dried-out seal strips can fail at much lower speeds.
How to check a roof after a derecho
- Walk the yard for shingle pieces, ridge caps and granule-covered debris. Note which side of the house they came from.
- Look along the eaves and rakes with binoculars for lifted, folded or missing tabs.
- Check where trees or large limbs touched the roof, even if they were removed, for cracked shingles or a soft deck.
- Book an inspection. A hands-on check of the seal strips on each slope is the only way to find shingles that are loose but still in place. Our page on high winds and Denver roofs covers more.
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 6 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 wind help
If you live in the Denver metro, start with our Denver storm 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
- May 30, 2024 Hailstorm: hail to 2.75 in.
- June 21 and 22, 2023 Hailstorms: hail to 2.5 in.
- June 18 and 19, 2018 Hailstorms: hail to 3 in.
- May 8, 2017 Denver hailstorm (full write-up)
- September 29, 2014 Hailstorm: hail to 1.75 in.
- June 6, 2012 hailstorm, Colorado Springs and south Denver (full write-up)
- July 13, 2011 Hailstorm: hail to 4.5 in.
- May 26, 2010 Hailstorm: hail to 2.75 in.
- Full storm archive: Colorado Springs, Denver and Austin
Sources: NOAA SPC storm reports, June 6, 2020; NOAA NCEI Storm Events Database, event 890371 (Parker, 70 kt measured); NOAA NCEI Storm Events Database, event 890227 (Aurora, 70 kt estimated); NWS Boulder, high wind information; C.R.S. 10-4-110.8 (unofficial reproduction); Colorado Division of Insurance, hail consumer advisory (May 22, 2024).
