Tornadoes · United States · Iowa
1931 tornadoes in Iowa
Grazulis's record has 11 significant tornadoes in Iowa in 1931. They killed 4 people and injured 52. 1 was rated F4 or above. Before 1950 the record is Thomas P. Grazulis’s list of significant tornadoes: those rated F2 or stronger, and weaker ones that killed somebody.
The rating scale
Tracks are drawn in the color of the rating. Grazulis rated these tornadoes on the Fujita scale decades after the fact, from written accounts of the damage. The scale rates the damage rather than measuring the wind: the speeds are what that damage is taken to imply.
F040 to 72 mph
Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.
F173 to 112 mph
Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.
F2113 to 157 mph
Considerable damage. Roofs torn off well-built houses, frame homes shifted on their foundations, mobile homes destroyed, large trees snapped or uprooted, cars lifted off the ground.
F3158 to 206 mph
Severe damage. Whole stories of well-built houses destroyed, large buildings badly damaged, trains overturned, trees debarked, heavy cars lifted and thrown.
F4207 to 260 mph
Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.
F5261 to 318 mph
Incredible damage. Strong frame houses swept off their foundations, car-sized missiles thrown more than 100 meters, steel-reinforced concrete badly damaged, high-rise buildings deformed.
Unrated
Grazulis gave no rating: the surviving account records a tornado without enough about the damage to rate it. Almost all of these are before 1880.
Every significant tornado in Iowa in 1931
Times are local standard time, where the record has one. Blank cells are not recorded.
April 18 1 tornado
| Date | Time | Rating | Where | Path (mi) | Width (yd) | Deaths | Injuries | Damage |
|---|---|---|---|---|---|---|---|---|
| April 18 | 4:30 PM CST | F2 | SW Fontanelle/S Stuart, IA | 24.0 | 70 |
May 17 1 tornado
| Date | Time | Rating | Where | Path (mi) | Width (yd) | Deaths | Injuries | Damage |
|---|---|---|---|---|---|---|---|---|
| May 17 | 5:30 PM CST | F2 | Ruth Lake, IA/E Lakefield, MN | 29.2 | 1 |
June 19 3 tornadoes
August 27 2 tornadoes
September 19 1 tornado
| Date | Time | Rating | Where | Path (mi) | Width (yd) | Deaths | Injuries | Damage |
|---|---|---|---|---|---|---|---|---|
| September 19 | 7:33 PM CST | F2 | S Elk Creek/NE Hanlontown, IA | 7.7 |
September 21 3 tornadoes
| Date | Time | Rating | Where | Path (mi) | Width (yd) | Deaths | Injuries | Damage |
|---|---|---|---|---|---|---|---|---|
| September 21 | 3:00 PM CST | F2 | E Bloomfield, IA | 6.3 | ||||
| September 21 | 3:15 PM CST | F2 | E Bloomfield/Floris, IA | 10.9 | 100 | 20 | ||
| September 21 | 3:30 PM CST | F4 | S Brighton to SE Cotter, IA | 45.9 | 100 | 2 | 8 |
About the record before 1950
- Significant tornadoes only
- Grazulis listed tornadoes rated F2 or stronger, and weaker ones that killed somebody. Most tornadoes are weaker than F2, so the list holds a fraction of the tornadoes that happened.
- The early years are thin
- A tornado is on record only where somebody saw it and wrote it down. The count rises through the 1800s with settlement and newspapers, not with the weather.
- Rated from accounts
- Grazulis rated each tornado decades later from newspaper reports, Weather Bureau records and local histories, not from a damage survey.
- The tracks are reconstructed
- Tornado Archive drew each path through the places Grazulis names, most often as a straight line from the first to the last. A track can miss a town it hit, and a tornado with one named place is a point. The counties are today’s.
- A separate record
- SPC’s database, from 1950, counts every confirmed tornado of any strength. The two are kept apart on every page and never added together.
Nearby
What this means
Ratings are Grazulis's, read from written accounts of the damage; the rating scale is above. About the record before 1950 says what it holds and what it leaves out.
Sources
Thomas P. Grazulis, Significant Tornadoes 1680-1991 and Significant Tornadoes 1880-1989, as digitized by Tornado Archive (Maas and others, 2024). Public domain. Counties assigned by this site from today’s NWS county lines.