Iowa has a long and well-documented history of severe storms, with 3,417 confirmed tornadoes, 15,434 hailstorm events and 17,186 damaging-wind events recorded by the National Weather Service since 1950. The state ranks 5th nationally for tornado frequency, and averages 45.6 tornadoes per year over the 75-year record. Iowa lies within Tornado Alley, the historic core of the country’s most active severe-weather climate. The interactive map below plots every significant severe-weather event in Iowa from the official NOAA Storm Events Database (1950 through September 2025).
Use the map to find your county, click any marker for the date, magnitude, and casualty details of that event, and switch between tornadoes, hail and wind using the chips. For the national view across all 50 states, see our NOAA Storm Reports interactive map. For tornado tracks specifically, see the US Tornado Tracks map; for hail size and frequency, the US Hailstorms map.
Iowa Severe Weather by the Numbers (1950–2025)
- 3,417 tornadoes recorded between 1950 and 2025
- 822 violent tornadoes rated F2/EF2 or stronger
- 10 confirmed F5/EF5 tornadoes on record — the maximum rating on the Fujita and Enhanced Fujita scales
- 99 direct tornado deaths and 2,335 direct injuries
- 15,434 hailstorm events recorded by the NWS
- 17,186 damaging-wind events on record
- 45.6 tornadoes per year on average across the 75-year record
- May is the peak severe-weather month, accounting for roughly 24.7% of Iowa tornadoes
- 176 total direct deaths from all severe-weather event types tracked by the NWS
When Iowa Severe Weather Happens
Iowa tornado activity is heavily concentrated in spring. March, April, May and June account for 69% of all Iowa tornadoes, with May alone responsible for roughly 24.7%.
- May: 844 tornadoes (24.7%) — peak month
- June: 827 tornadoes (24.2%)
- April: 469 tornadoes (13.7%)
- July: 373 tornadoes (10.9%)
- August: 287 tornadoes (8.4%)
- March: 204 tornadoes (6%)
Top 10 Iowa Counties by Tornado Frequency
Tornado activity in Iowa is geographically broad, but a handful of counties have logged many times the state average. The combination of population density (more spotters and damage reports), county land area and local climatology drives the rankings below.
| County | Tornadoes since 1950 |
|---|---|
| Polk | 68 |
| Scott | 65 |
| Webster | 65 |
| Linn | 61 |
| Story | 61 |
| Dallas | 58 |
| Pottawattamie | 57 |
| Woodbury | 57 |
| Hamilton | 56 |
| Boone | 52 |
The Deadliest Tornadoes in Iowa History
Iowa has lost 99 lives to tornadoes since the National Weather Service began systematic tornado record-keeping in 1950. The single deadliest event killed 13 people in Floyd County in 1968, rated F5 on the Fujita scale.
| Date | Location | Rating | Direct deaths | Direct injuries |
|---|---|---|---|---|
| May 15, 1968 | Floyd County | F5 | 13 | 450 |
| May 25, 2008 | Butler County (near Aplington) | EF5 | 9 | 50 |
| October 14, 1966 | Wright County | F5 | 6 | 172 |
| March 5, 2022 | Madison County (near Macksburg) | EF4 | 6 | 5 |
| May 15, 1968 | Fayette County | F5 | 5 | 156 |
| September 16, 1978 | Poweshiek County | F3 | 4 | 43 |
| June 11, 2008 | Monona County (near Blencoe) | EF3 | 4 | 48 |
| May 21, 2024 | Adair County (near Fisk) | EF4 | 4 | 35 |
| June 28, 1979 | Calhoun County | F4 | 3 | 26 |
| April 16, 1967 | Van Buren County | F3 | 2 | 16 |
Iowa Tornado Strength Distribution
Most Iowa tornadoes are weak: roughly 74% are rated F0/EF0 or F1/EF1. Violent tornadoes (F2+/EF2+) account for around 26% of rated tornadoes in the state. Iowa is one of the few states with a confirmed F5 or EF5 tornado on record.
- F0/EF0 (weak): 1,328 tornadoes — 42% of rated events
- F1/EF1: 1,015 tornadoes — 32.1% of rated events
- F2/EF2 (strong): 582 tornadoes — 18.4% of rated events
- F3/EF3: 150 tornadoes — 4.7% of rated events
- F4/EF4 (violent): 80 tornadoes — 2.5% of rated events
- F5/EF5 (incredible): 10 tornadoes — 0.3% of rated events
Record-Setting Severe Weather in Iowa
Largest hailstone: 8.00 inches in diameter, observed in Fayette County on May 31, 1958. The three largest hailstones on record in Iowa measured 8.00″, 7.00″, 5.50″.
Highest measured wind gust: 126 knots (145 mph) recorded in Benton County near Belle Plaine Arpt on August 10, 2020. Most damaging-wind events in Iowa are estimated rather than measured because anemometers are sparse across the rural areas where supercells most often produce destructive thunderstorm winds.
How Iowa Compares Nationally
Iowa is one of the top severe-weather states in the country, ranking 5th nationally for tornado frequency since 1950.
- Tornadoes (top 5): Texas (9,908), Kansas (4,890), Oklahoma (4,856), Florida (3,779), Iowa (3,417).
- Iowa tornado total: 3,417 — ranked 5th nationally.
- Iowa hail total: 15,434 hail events on record since 1950.
- Iowa wind total: 17,186 damaging-wind events on record since 1950.
Frequently Asked Questions
How many tornadoes does Iowa have on average per year?
Iowa averages 45.6 tornadoes per year over the 1950–2025 period. Counts vary widely year to year, but the long-term mean over 75 years of NWS records is a reliable benchmark for typical activity.
What was the deadliest tornado in Iowa history?
The May 15, 1968 tornado, rated F5 on the Fujita scale, killed 13 people and injured 450 in Floyd County. It remains the single deadliest tornado in the Iowa modern record.
Where in Iowa are tornadoes most common?
The single county with the most tornadoes on record is Polk County with 68 events. The three most active counties overall are Polk, Scott, Webster.
How does Iowa compare to its neighbors?
Iowa shares a severe-weather climate with Minnesota, Wisconsin, Illinois, Missouri, Nebraska, South Dakota. Severe storms regularly cross state lines, so the same supercells, hail cores and wind events often appear in Iowa’s neighbors’ records on the same date.
How recent is the data on this map?
The map and statistics on this page are pulled from NOAA’s official Storm Events Database, which currently runs from January 1950 through September 2025. New records typically appear in the database within 30–90 days of the event date, once damage surveys and ratings are complete.
Compare Iowa to Neighboring States
Severe weather doesn’t stop at state lines. The same supercell systems that produce Iowa tornadoes regularly cross into neighboring states. Compare Iowa’s storm history to its land neighbors:
- Minnesota severe storm history — ranked 14th nationally
- Wisconsin severe storm history — ranked 18th nationally, Great Lakes severe-weather and lake-effect winters
- Illinois severe storm history — ranked 6th nationally, Great Lakes severe-weather and lake-effect winters
- Missouri severe storm history — ranked 10th nationally, Dixie Alley state with frequent overnight tornadoes
- Nebraska severe storm history — ranked 7th nationally, core Tornado Alley state
- South Dakota severe storm history — ranked 17th nationally, core Tornado Alley state
Explore the national NOAA Storm Reports map · US Tornado Tracks map · US Hailstorms map
