40
Recorded events
0
Direct deaths
20
Direct injuries
$32.7M
Property damage
Tornado in Delaware County, Iowa: 40 recorded events between 1960 and 2026. The strongest on record measured F4. That places the county #620 nationally and #32 statewide for this hazard.
Decade by decade
Tornado in Delaware County, Iowa: events per decade
Reporting practice changed over time — early decades are undercounted, not calmer.
The busiest decade for tornado in Delaware County is the 1990s, when 7 of the county's 40 recorded events were logged. Comparing decades is useful for spotting active periods, but the earliest years are thin because systematic reporting for this hazard began later.
Within the Delaware County archive, tornado makes up 8.6% of all recorded severe weather across 8 hazard types. Nationally the county sits at #620 for this hazard and #32 within Iowa, putting it in the 78.6 percentile of all U.S. counties.
Seasonality
Events by month
May is the peak month for tornado in Delaware County with 9 recorded events, while Jan is the quietest. Seasonality here is a property of the archive as much as the climate: reports cluster where population and spotter networks are densest.
Tornado tracks
Paths crossing this county
| Date | Scale | Path length | Max width | Origin |
|---|---|---|---|---|
| 1990-03-13 | EF4 | 19.0 mi | 200 yd | Crossed in |
| 1974-08-12 | EF4 | 5.0 mi | 400 yd | Touched down here |
| 1954-04-30 | EF4 | 80.4 mi | 200 yd | Crossed in |
| 2008-05-25 | EF3 | 32.0 mi | 1,232 yd | Crossed in |
| 1995-07-27 | EF3 | 20.0 mi | 150 yd | Crossed in |
| 1993-06-19 | EF3 | 9.0 mi | 200 yd | Touched down here |
| 1971-07-12 | EF3 | 0.1 mi | 833 yd | Touched down here |
| 2017-06-28 | EF2 | 2.5 mi | 30 yd | Crossed in |
| 1991-03-22 | EF2 | 17.0 mi | 80 yd | Touched down here |
| 1990-06-02 | EF2 | 10.5 mi | 67 yd | Crossed in |
Significant events
Deadliest on record
| Date | Location | Scale | Deaths | Injuries | Damage |
|---|---|---|---|---|---|
| Aug 12, 1974 | F4 | 0 | 12 | $2.5M | |
| Aug 7, 1986 | F1 | 0 | 3 | $25K | |
| Jul 13, 1971 | F3 | 0 | 2 | $2.5M | |
| May 5, 1964 | F2 | 0 | 2 | $250K | |
| Mar 23, 1991 | F2 | 0 | 1 | $250K |
Most recent
Latest recorded events
| Date | Location | Magnitude | Damage |
|---|---|---|---|
| Apr 14, 2026 | MASONVILLE | EF1 | $0 |
| Jul 11, 2025 | BUCK CREEK | EF0 | $0 |
| Mar 31, 2023 | ONEIDA | EF1 | $0 |
| Mar 31, 2023 | MANCHESTER | EF1 | $0 |
| Jul 15, 2021 | BUCK CREEK | EFU | $0 |
| Jul 15, 2021 | MANCHESTER | EF1 | $0 |
| Jul 15, 2021 | COFFINS GROVE PARK | EF1 | $0 |
| Jun 9, 2019 | MASONVILLE | EFU | $0 |
| Jun 29, 2017 | SAND SPG | EF2 | $0 |
| Jul 23, 2016 | TURTLE CREEK PARK | EF1 | $0 |
Other hazards here
More from Delaware County
- Thunderstorm Wind 219
- Hail 152
From the record
What the reports say
Written by National Weather Service staff at the time of the event · public domain
Continued from Linn County. An EF1 tornado with estimated wind speeds of up to 100 mph touched down near Lafayette, IA around 452 pm and proceeded to track northeast crossing the Linn-Delaware County line around 510 pm, finally lifting just north of Buck Creek, IA around 530 pm. Several farms sustained structural and equipment damage, trees were uprooted or snapped off, some camping trailers were destroyed, and several power lines were blown down.
A tornado formed 4 miles south of Lamont, IA in Buchanan County, tracked about 1 mile to the northeast before crossing into Delaware County. In Delaware County the tornado continued for about 13 miles to the northeast to Edgewood, IA. ||This entry is for the Delaware County portion of the tornado track (second and final segment).||Most of the damage was south and east of Dundee into south Edgewood. Several grain bins collapsed or were destroyed. Two old hog confinements were seriously damaged along with an aluminum roof being torn off. Numerous trees were snapped along the path.
A tornado touched down southwest of Petersburg and moved east for approximately 7 miles to the Delaware-Dubuque county line. Along its path, trees, power poles, and numerous farm outbuildings were damaged. It continued to track into Dubuque County.
Quick answers
Frequently asked
How many tornado events are on record in Delaware County, Iowa?
40 tornado events are recorded in Delaware County between 1960 and 2026, causing 0 direct deaths.
What is the strongest tornado recorded in Delaware County?
The strongest tornado on record in Delaware County measured F4.
Where does the tornado data for Delaware County come from?
All events come from the NOAA/NCEI Storm Events Database, the federal public-domain archive of severe weather reports. Dates are UTC, damage is as reported and not inflation-adjusted, and the most recent entries may still be revised.
Cite this page
“Tornado in Delaware County, Iowa.” Severe Weather History. severeweatherhistory.com/county/iowa/delaware-county/tornado/ · Data: NOAA/NCEI, FEMA, U.S. Census — public domain.