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Johnson County, Iowa severe weather history spans 652 recorded events between 1958 and 2026. The dominant hazard is thunderstorm wind, accounting for 42.0% of all recorded events. It ranks #471 nationally and #16 in Iowa.
652
Recorded events
2
Direct deaths
66
Direct injuries
$337.3M
Property damage
The record
What the Johnson County, Iowa severe weather history record shows
Across the archive, Johnson County, Iowa severe weather history averages 9.6 recorded events a year. The busiest stretch on record is the 2010s, with 193 events logged in that decade alone. Roughly 88 events fall before 1990 and 564 from 1990 onward — a gap that reflects the expansion of NOAA reporting practice as much as the weather itself.
The deadliest hazard in the Johnson County, Iowa record is thunderstorm wind, responsible for 1 direct deaths. The costliest is flood, with $230.7M in reported property damage. In total, 9 distinct hazard types appear in this county archive, each listed with its own dated record below.
By hazard type
Every hazard type recorded in Johnson County
| Hazard | Events | Deaths | Damage | Max | Span |
|---|---|---|---|---|---|
| Thunderstorm Wind | 274 | 1 | $31.8M | 83 | 1958–2026 |
| Hail | 229 | 0 | $40.5M | 2.75 | 1968–2026 |
| Flash Flood | 49 | 0 | $3.3M | 0 | 1997–2024 |
| Tornado | 46 | 1 | $30.0M | F3 | 1962–2026 |
| Funnel Cloud | 19 | 0 | $0 | 0 | 1998–2015 |
| Flood | 17 | 0 | $230.7M | 0 | 1999–2018 |
| Lightning | 10 | 0 | $1.1M | 0 | 2006–2015 |
| Heavy Rain | 7 | 0 | $2K | 1.5 | 2003–2011 |
| Winter Weather | 1 | 0 | $0 | 0 | 2001–2001 |
Decade by decade
Johnson County, Iowa severe weather history by decade
Reporting practice changed over time — early decades are undercounted, not calmer.
Tornado tracks
Paths crossing this county
47 mapped tornado paths intersect this county: 36 touched down inside it and 11 crossed in from a neighbouring county. This comes from path geometry, not county-tagged reports.
| Date | Scale | Deaths | Injuries | Path length | Origin |
|---|---|---|---|---|---|
| 2023-03-31 | EF4 | 0 | 3 | 19.9 mi | Crossed in |
| 1998-05-15 | EF3 | 0 | 47 | 47.0 mi | Crossed in |
| 1962-05-22 | EF2 | 1 | 0 | 4.1 mi | Touched down here |
| 2023-03-31 | EF2 | 0 | 0 | 14.7 mi | Touched down here |
| 2023-03-31 | EF2 | 0 | 0 | 9.0 mi | Touched down here |
| 2023-03-31 | EF2 | 0 | 2 | 16.9 mi | Touched down here |
| 2006-04-13 | EF2 | 0 | 30 | 4.5 mi | Touched down here |
| 1991-09-12 | EF2 | 0 | 0 | 7.0 mi | Touched down here |
| 1991-03-22 | EF2 | 0 | 0 | 14.0 mi | Touched down here |
| 1989-04-27 | EF2 | 0 | 0 | 18.0 mi | Crossed in |
Significant events
Deadliest events on record in Johnson County
| Date | Type | Location | Deaths | Injuries | Damage |
|---|---|---|---|---|---|
| May 29, 2011 | Thunderstorm Wind | LAKE MACBRIDE SP | 1 | 0 | $10K |
| May 23, 1962 | Tornado | 1 | 0 | $250K | |
| Apr 14, 2006 | Tornado | IOWA CITY | 0 | 30 | $12.0M |
| May 15, 1998 | Tornado | HILLS | 0 | 17 | $6.0M |
| Jun 29, 1998 | Thunderstorm Wind | COUNTYWIDE | 0 | 12 | $30.7M |
| Mar 31, 2023 | Tornado | COSGROVE | 0 | 2 | $0 |
| Apr 29, 1974 | Tornado | 0 | 2 | $25K | |
| Jun 30, 2014 | Thunderstorm Wind | NORTH LIBERTY | 0 | 1 | $0 |
From the record
What the reports say
Written by National Weather Service staff at the time of the event · public domain
The record crest on the Iowa River at Iowa City occurred on June 15, 2008 at 31.53 feet. Flood stage is 22 feet. The record crest on the Iowa River at Lone Tree occurred on June 15, 2008 at 23.15 feet. Flood stage is 15 feet. Preliminary damage estimates just to the University of Iowa at Iowa City was at least $230 million. This compares to $6 million in damages during the Great Flood of 1993. Water flowed over the spillway at the Corps of Engineer's Coralville Reservoir for only the third time since the reservoir began operation on September 17, 1958. (The previous two times occurred in the summer of 1993). The result was unprecedented flooding downstream of the reservoir in the cities of Iowa City and Coralville.
A 15 minute "rain" of baseball sized hail caused $30 to $50 million dollars of damage. One insurance agent said "this was the worst storm since 1967." He went on to say; "everyone he insures who has a skylight now has a broken skylight." This included the skylights over the swimming pool in the downtown Iowa City Holliday Inn. The average home claim was $3500 and the average car claim was $2500. The hail caused widespread damage to individuals cars and between 300 and 500 thousand dollars worth of damage to each of four car dealerships interviewed.
Reports of urban flash flooding were received from around Iowa City. 8 to 10 inches of water covered a parking lot at a radio station, stranding 5 employees. 4 of the 5 were evacuated by the fire department. Numerous major streets were closed, and some businesses suffered minor flooding damage.
Context
Risk, population and federal disasters
Relatively Moderate
FEMA NRI risk rating
156,639
Population (ACS)
$309K
Median home value
24
Federal declarations
| Declared | Incident | Title | Type |
|---|---|---|---|
| Aug 17, 2020 | Severe Storm | SEVERE STORMS | DR |
| Mar 23, 2020 | Biological | COVID-19 PANDEMIC | DR |
| Mar 13, 2020 | Biological | COVID-19 | EM |
| Aug 5, 2014 | Severe Storm | SEVERE STORMS, TORNADOES, STRAIGHT-LINE WINDS, AND FLOODING | DR |
| Jul 2, 2013 | Severe Storm | SEVERE STORMS, TORNADOES, AND FLOODING | DR |
| May 31, 2013 | Flood | SEVERE STORMS, STRAIGHT-LINE WINDS, AND FLOODING | DR |
Within the county
Most affected places
- Iowa City 139
Quick answers
Frequently asked
How many severe weather events have been recorded in Johnson County, Iowa?
652 events are on record between 1958 and 2026, causing 2 direct deaths and $337.3M in property damage.
What is the most common severe weather hazard in Johnson County?
Thunderstorm Wind, with 274 recorded events — 42.0% of everything in the archive for this county.
How many tornadoes have crossed Johnson County?
47 mapped tornado paths intersect the county boundary; 36 of them touched down inside it. This is derived from path geometry, not county-tagged reports.
How many federal disaster declarations cover Johnson County?
24 federal disaster declarations from FEMA include Johnson County, each tied to a specific incident period.
How risky is Johnson County compared with the rest of the country?
FEMA's National Risk Index rates Johnson County as relatively moderate risk, placing it in the 87 percentile of its state for expected annual loss.
Where does the Johnson County, Iowa severe weather history data come from?
Every figure is drawn from United States federal public-domain records: NOAA/NCEI Storm Events for the event archive, NOAA SPC SVRGIS for mapped tornado paths, FEMA for disaster declarations and risk ratings, and the U.S. Census for population context. Dates are shown in UTC and recent entries may still be revised by NOAA.
Nearby
Neighbouring counties
- Jefferson County 256
- Jones County 491
- Jasper County 577
- Keokuk County 282
- Jackson County 329
- Kossuth County 568
Cite this page
“Johnson County, Iowa.” Severe Weather History. severeweatherhistory.com/county/iowa/johnson-county/ · Data: NOAA/NCEI, FEMA, U.S. Census — public domain.