Iowa, 1977

Tornadoes and Damaging Winds in Iowa, May 4, 1977

May 4, 1977 · 17 events in 12 counties and zones

14 tornado, 3 thunderstorm wind, as filed by the National Weather Service.

Where it happened

Every event with a place to put it. Tap one for its entry below.

  • Tornadoes
  • Tropical storms and surge
  • Floods
  • Wind
  • Hail
  • Winter weather
  • Heat and drought
  • Cold
  • Fire, smoke and dust
  • Marine and coastal
  • Other

Open the live radar over this ground

The toll

Deaths
0
Injuries
19
Property damage
$3.7 million
Crop damage
None recorded
Events
17

Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.

Event by event

14 tornado, 3 thunderstorm wind. Local standard time, as filed.

Tornado, Davis

When
May 4, 1:58 PM CST
Where
Davis County
Rating
F1
Path length
4.3 mi
Path width
20 yd
Property damage
$25,000
Coordinates
40.720, -92.370

Thunderstorm Wind, Wapello

When
May 4, 2:16 PM CST
Where
Wapello County
Measured
54 kt (62 mph)
Coordinates
41.100, -92.450

Tornado, Lee

When
May 4, 2:30 PM CST
Where
Lee County
Rating
F2
Path length
2 mi
Path width
60 yd
Property damage
$250,000
Coordinates
40.780, -91.600

Thunderstorm Wind, Van Buren

When
May 4, 2:30 PM CST
Where
Van Buren County
Coordinates
40.730, -91.950

Tornado, Des Moines

When
May 4, 2:56 PM CST
Where
Des Moines County
Rating
F2
Path length
2 mi
Path width
10 yd
Property damage
$25,000
Coordinates
40.870, -91.300

Tornado, Henry

When
May 4, 3:00 PM CST
Where
Henry County
Rating
F2
Path width
30 yd
Injuries
1 direct, 0 indirect
Property damage
$250,000
Coordinates
40.970, -91.550

Tornado, Henry

When
May 4, 3:10 PM CST
Where
Henry County
Path width
20 yd
Property damage
$25,000
Coordinates
41.130, -91.480

Tornado, Louisa

When
May 4, 3:15 PM CST
Where
Louisa County
Path width
33 yd
Property damage
$25,000
Coordinates
41.170, -91.470

Tornado, Webster

When
May 4, 6:20 PM CST
Where
Webster County
Rating
F2
Path length
1 mi
Path width
70 yd
Injuries
4 direct, 0 indirect
Property damage
$2.5 million
Coordinates
42.470, -94.220

Tornado, Pocahontas

When
May 4, 6:30 PM CST
Where
Pocahontas County
Path length
1 mi
Path width
10 yd
Property damage
$3,000
Coordinates
42.550, -94.870

Tornado, Webster

When
May 4, 6:32 PM CST
Where
Webster County
Rating
F4
Path length
2 mi
Path width
70 yd
Injuries
14 direct, 0 indirect
Property damage
$250,000
Coordinates
42.530, -94.150

Tornado, Guthrie

When
May 4, 7:15 PM CST
Where
Guthrie County
Path length
1 mi
Path width
33 yd
Coordinates
41.780, -94.530

Tornado, Guthrie

When
May 4, 7:26 PM CST
Where
Guthrie County
Path length
1 mi
Path width
30 yd
Property damage
$25,000
Coordinates
41.850, -94.570

Thunderstorm Wind, Webster

When
May 4, 7:43 PM CST
Where
Webster County
Measured
51 kt (59 mph)
Coordinates
42.550, -94.180

Tornado, Boone

When
May 4, 8:30 PM CST
Where
Boone County
Path width
10 yd
Property damage
$25,000
Coordinates
42.070, -93.880

Tornado, Tama

When
May 4, 9:00 PM CST
Where
Tama County
Path length
17.8 mi
Path width
30 yd
Property damage
$250,000
Coordinates
42.100, -92.680

Tornado, Tama

When
May 4, 10:15 PM CST
Where
Tama County
Path length
1 mi
Path width
20 yd
Property damage
$25,000
Coordinates
42.180, -92.720

What these are

Tornado
A violently rotating column of air in contact with the ground and extending from a thunderstorm, filed with its path, width and Fujita or Enhanced Fujita rating from the damage survey.
Thunderstorm Wind
Winds from a thunderstorm of 50 knots (58 mph) or more, or lower winds that caused damage or casualties. Measured gusts are marked MG, estimated EG.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

More

Every storm in Iowa in 1977Every state in 1977This day in weather historyThe tornado archive for Iowa, 1977

Sources

NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 10014987, 10014988, 10014989, 10014990, 10014991, 10014992, 10014993, 10014994, 10014995, 10014996, 10014997, 10014998, 10014999, 10015000, 10015001, 10015002, 10015003.