The Enhanced Fujita Scale, or EF Scale, is used to assign a tornado a rating based on estimated wind speeds and related damage. When tornado-related damage is surveyed, it is compared to a list of damage indicators and degrees of damage, which help estimate better the range of wind speeds the tornado likely produced. From that, a rating from EF0 to EF5 is assigned. From 1974 to 2007, the
Fujita Scale was used to calculate the strength of a tornado. This system had calculated the strength based on the damage delt to well-built wooden homes. Tornadoes recorded before 1974 were examined and rated accordingly. Multiple flaws including a lack of damage indicators, difference in opinion from evaluators, and no calibration of damage with relation to wind speed caused researchers from
Texas Tech University to re-examine and re-do the Fujita Scale. A group of wind data experts met in 2001 and came up with 28 new damage indicators which included poles, trees, and other buildings other than just wooden frame homes. After discussion, the
National Weather Service officially adopted the new scale in 2007.
Pre-1900 A total of 142 recorded tornadoes touched down in Iowa before 1900. At least 540 people died and 2,186 people were injured due to these tornadoes before 1900. There have been 63 intense tornadoes with a rating of F3+, the deadliest of which was on June 3, 1860, in
Camanche, killing 92. This time period for tornadoes in Iowa is the deadliest period of tornadoes in Iowa, with each recorded tornado killing on average 3.48 people. The first use of a tornado warning in the United States wasn't until March 25, 1948. This caused tornadoes before the 1950s to be more dangerous, because people thought that tornadoes would be too rare to strike a region so there was no point in issuing warnings.
Camanche Tornado On June 3, 1860, an
F4 tornado touched down north of
Bennett, moving across eastern Iowa, killing 20 people in rural
Clinton County. It then ripped through
Camanche, destroying almost every building in the town and killing 41. A raft carrying 26 was hit by the tornado and flipped, killing all but 3 men. The tornado caused an estimated $250,000 - $300,000 in damages.
Grinnell Tornado On June 17, 1882, two tornadoes formed and intersected in Grinnell forming one tornado at F5 intensity. It travelled across central Iowa, killing a total of 68 people. 10 people died near
Rippey, 7 people died in
Jasper County, 39 in
Grinnell, and 10 in
Malcolm.
Pomeroy Tornado On July 6, 1893, an F5 tornado touched down northwest of
Quimby, moving toward the town of
Pomeroy. With a damage path 500 yards (460 m) wide and 55 miles (89 km) long, the tornado destroyed about 80% of the homes in Pomeroy. The tornado killed 71 people and injured 200.
1900–1949 A total of 338 tornadoes touched down in Iowa between 1900 and 1949. At least 292 people died and 1,861 people were injured. There were 75 intense F3+ tornadoes, the deadliest of which was the
1913 Easter tornado that hit
Omaha, Nebraska, making its way over the border into Iowa, killing a total of 103 people and injuring 350 others.
Omaha Easter Sunday Tornado An F4 tornado touched down in
La Vista, Nebraska, a
suburb of
Omaha, traveling through the city of Omaha and crossing the border into Iowa. In total, 103 people died, 9 of whom were in Iowa. The tornado had a damage path of 40.3 mi (64.86 km) long and 400 yds (365.76 m) wide.
Crawford County Tornado On May 21, 1918, an F5 tornado touched down in
Crawford County, moving across the county and into
Greene County as well. According to witnesses, twenty or more farms were destroyed and a couple riding in a buggy north of
Churdan were caught by the tornado and died. Mattresses were carried two miles away and farms and homes were wiped completely off their foundations.
1950–present A total of 3,118 recorded tornadoes have touched down in Iowa since 1950, causing 101 deaths and injuring 2,400 as of July 2025. There have been 20 (E)F5 tornadoes, or 2 or more fatalities, the deadliest being the
1968 Hansell-Charles City tornado, which killed 13 and injured 462.
1968 Hansell-Charles City tornado On May 15, 1968, a
multi-vortex tornado hit the communities of
Hansell,
Hampton,
Charles City,
Elma, and
Aredale, all in
Iowa. It killed 13, injured 462, and hundreds of buildings were destroyed, primarily in the town of Charles City. Damage estimates were of more than $20 million. All of the deaths occurred in Charles City.
2008 Parkersburg-New Hartford tornado On the afternoon of May 25, 2008, as part of a
large tornado outbreak across the central plains, a large and extremely powerful
EF5 wedge
tornado devastated the towns of
Parkersburg and
New Hartford. The tornado killed nine people and caused about $75 million in damages in its approximately 43 mile path across northeast Iowa. The tornado killed 7 in Parkersburg and 2 in New Hartford.
2024 Greenfield tornado On the afternoon of May 21, 2024, a violent
tornado tracked across southwestern Iowa, devastating the city of
Greenfield. The tornado destroyed many structures and
wind turbines across its path that stretched through
Page,
Taylor,
Adams, and
Adair counties, while also causing more than $31 million in property damage, killing five people and injuring 35 more. All of the fatalities happened in the town of Greenfield. A
Doppler on Wheels estimated wind speeds of 309–318 mph (497–512 km/h), the third highest wind estimate from inside a tornado in the United States, before the
2013 El Reno tornado and the
Bridge Creek tornado. == Notes ==