Waterloo hail storm history
Black Hawk County·NOAA NCEI Storm Events Database·~75-day publication lag
Waterloo, located in Black Hawk County, has experienced 8 hail events of 1 inch or larger over the past 10 years, averaging 0.8 events annually. The largest recorded hailstone in the county measured 1.25 inches, which fell on September 16, 2025, and represents the marginal damage threshold where granule loss becomes probable on aging roof shingles. Black Hawk County's position in eastern Iowa places it in a corridor where organized storm systems from the central Plains track northeast.
Hail in Waterloo occurs most frequently during May and June, when mesoscale convective systems and squall lines from the central Plains move through the region. Secondary activity extends into April and July, with derecho events also common along this summer corridor. The peak months of May and June account for the majority of damaging hail events in the area.
Annual frequency — last 10 years
When hail hits — monthly pattern
Avg events per month · all years · NOAA data
All recorded hail events
Of 186 recorded events, 54 (29%) reached 1.5" or larger — the threshold for likely functional damage on standard asphalt shingles.
Social media image of quarter sized hail. Relayed by KWWL. Time estimated from radar.
A delayed report via social media.
Spotter submitted picture of hail larger than a quarter north of Irvine Prairie. Delayed report, tim…
A trained spotter reported dime to quarter sized hail. The hail was covering the ground and accompan…
Hail ranged from pea to ping pong ball sized. Report relayed by kwwl tv.
Numerous hailstones pictured with the largest up to ping pong ball sized.
A trained spotter reported pea to nickel size hail.
Hail reported from a trained spotter. Time estimated from radar.
Report by kwwl tv.
Spotter submitted a photo of quarter-sized hail 5 miles north of Dysart. Report received was delayed…
Dime to quarter sized hail reported.
Submitted picture of half dollar sized hail in Elk Run Heights.
Quarter sized hail reported in Dike. Photo and video relayed via broadcast media. Time estimated fro…
The time was based on radar data.
Hail reported along highway 14 just south of Allison.
Delayed report of hail up to half dollar sized.
Trained spotter reported quarter sized hail near Oelwein.
KWWL forwarded report of golf ball sized hail.
Public reported quarter sized hail via mPing app.
Report via social media, time estimated by radar.
Delayed report, image submitted via social media.
Delayed report via social media. Time estimated by radar.
Delayed report via social media of ping pong ball sized hail north of Grundy Center. Time estimated …
Strong winds reported with quarter sized hail. Relayed by KWWL.
Photo of a nickel next to a slightly smaller hail stone.
Quarter sized hail in progress with heavy rain at time of report. End time estimated by radar.
Trained spotter reported penny sized hail with 50 mph wind gusts.
The COOP observer near Stanley reported dime to penny sized hail.
Quarter sized hail fell in Maynard.
KWWL relayed a public report and picture of roughly quarter sized hail south of Hudson.
KWWL relayed a public report of golf ball sized hail.
WOI-TV relayed a report of half dollar sized hail. Delayed report. Time estimated via radar.
A trained spotter reported quarter sized hail.
Fire Department reported quarter sized hail mixed with smaller hail lasting approximately ten minute…
Trained spotter reported nickel sized hail.
Public reported quarter sized hail via the mPING app.
A trained spotter reported nickel to quarter size hail.
Trained spotter reported quarter sized hail.
Trained spotter reported penny sized hail.
Trained spotter reported mostly pea to nickel sized hail, but a few stones as large as quarters were…
Public reported nickel sized hail.
KWWL relayed a public report of quarter sized hail.
This is a delayed report. Public reported larger than quarter sized hail in Traer via multiple repor…
Up to quarter sized hail fell in Oelwein.
Public reported quarter sized hail via social media.
Amateur radio operator reported quarter sized hail.
Trained spotter reported quarter sized hail.
Amateur radio operator reported golf ball sized hail.
Emergency manager reported half dollar sized hail.
Trained spotter reported quarter sized hail.
Emergency manager reported their truck sustained hail damage from hail just under golf ball size jus…
Public reported quarter sized hail along with estimated winds of 40 to 50 mph.
Golf ball sized hail fell in Oelwein.
Fifty mph winds were observed as well.
Public reported copious amounts of small pea to penny sized hail. Report relayed via KWWL. Time ra…
The National Oceanic and Atmospheric Administration (NOAA) maintains the Storm Events Database, which records hail events of 1 inch or larger across all U.S. counties. Black Hawk County's count of 10 documented events reflects the density and reliability of NOAA's reporting network in this region. Current-year data is excluded from the annual frequency table until October, when NOAA's Storm Events Database has processed the full hail season accounting for the standard 75-day reporting lag.
NOAA Storm Events Database source