F0/EF0 1 2 3 4 5 · Lines run from where each tornado touched down to where it lifted; dots are short paths. Neighboring counties are outlined.
When tornadoes hit Johnson County
April has brought the most, 14 of 46. About 67% touched down between 3 pm and 9 pm (Central Standard Time, as the Storm Prediction Center records it).
By decade
More tornadoes in recent decades mostly reflects better detection and reporting (Doppler radar, storm spotters, damage surveys), especially for weak EF0 tornadoes, not necessarily more storms. The 2020s bar covers only 2020 to 2024.
How strong they were
| Rating | Estimated 3-second gust | Tornadoes |
|---|---|---|
| F0 / EF0 | Light damage: 65 to 85 mph (EF scale) | 13 |
| F1 / EF1 | Moderate: 86 to 110 mph | 20 |
| F2 / EF2 | Considerable: 111 to 135 mph | 11 |
| F3 / EF3 | Severe: 136 to 165 mph | 1 |
| F4 / EF4 | Devastating: 166 to 200 mph | 1 |
| F5 / EF5 | Incredible: over 200 mph | 0 |
Tornadoes before February 2007 were rated on the original Fujita (F) scale; since then the National Weather Service uses the Enhanced Fujita (EF) scale. Wind speeds above are EF-scale estimates from damage, not measurements. See what the EF scale means.
The strongest tornadoes in Johnson County
| Date | Rating | Path length | Path width | Deaths | Injuries |
|---|---|---|---|---|---|
| March 31, 2023 | EF4 | 19.9 mi | 700 yd | 3 | |
| May 15, 1998 | F3 | 47 mi | 400 yd | 47 | |
| May 22, 1962 | F2 | 4.1 mi | 800 yd | 1 | |
| April 13, 2006 | F2 | 4.5 mi | 587 yd | 30 | |
| April 21, 1973 | F2 | 13.2 mi | 10 yd | 6 | |
| March 31, 2023 | EF2 | 16.9 mi | 75 yd | 2 | |
| June 7, 1984 | F2 | 24 mi | 200 yd | 1 | |
| May 8, 1988 | F2 | 59 mi | 60 yd | ||
| May 8, 1988 | F2 | 36 mi | 60 yd | ||
| March 22, 1991 | F2 | 14 mi | 80 yd |
Deaths and injuries are for each tornado’s whole path, which can cross other counties.
The deadliest
The deadliest tornado to touch Johnson County was an EF1 on April 27, 2014. It killed 2 people and injured 0 along its 45.7-mile path.
Most recent tornadoes
| Date | Rating | Path length | Path width | Deaths | Injuries |
|---|---|---|---|---|---|
| May 24, 2024 | EF0 | 0.1 mi | 50 yd | ||
| May 24, 2024 | EF1 | 15 mi | 75 yd | ||
| May 24, 2024 | EF1 | 22.5 mi | 150 yd | ||
| May 24, 2024 | EF1 | 18.3 mi | 100 yd | ||
| March 31, 2023 | EF2 | 9 mi | 75 yd | ||
| March 31, 2023 | EF2 | 14.7 mi | 100 yd | ||
| March 31, 2023 | EF2 | 16.9 mi | 75 yd | 2 | |
| March 31, 2023 | EF0 | 6.1 mi | 50 yd |
The official database ends with 2024. For storms since then, see the Storm Prediction Center’s reports and your local National Weather Service office.
FEMA’s tornado risk rating
FEMA’s National Risk Index rates the tornado risk in Johnson County as relatively high, with a score of 98 out of 100 compared with every other U.S. county. It estimates about 0.59 tornadoes a year here and an expected annual loss of about $36,235,301 to buildings, people and farming. The index mixes how often tornadoes strike with what is exposed and how well a community can recover, so a busy rural county can rate lower than a less active city.
Neighboring counties
- Linn County, IA: 63 tornadoes
- Cedar County, IA: 44 tornadoes
- Muscatine County, IA: 39 tornadoes
- Iowa County, IA: 37 tornadoes
- Washington County, IA: 25 tornadoes
- Louisa County, IA: 18 tornadoes
Staying safe
When a tornado warning is issued, act at once. Go to a basement, storm shelter or safe room. With none, use a small windowless room on the lowest floor, as far from outside walls as you can, and cover your head and neck. Mobile homes and cars are not safe places to ride out a tornado: leave early for a sturdy building or shelter. Read the full tornado safety guide and the National Weather Service advice linked below.
Sources
- NOAA Storm Prediction Center: Severe Weather Database, tornadoes 1950 to 2024 (public domain)
- FEMA National Risk Index, tornado county data (December 2025 release)
- NOAA Storm Prediction Center: The Enhanced Fujita Scale (EF scale)
- National Weather Service: Tornado safety
Sources last checked 1 November 2026.