Monona County, IA Environment & Hazard Risk

• DroughtRelatively Moderate$1.64M/yr expected annual loss, about 26 events a year
• HailRelatively Moderate$1.04M/yr expected annual loss, about 6.1 events a year
• LandslideRelatively Low$11.42K/yr expected annual loss, about once every 3 years
• WildfireRelatively Low$112K/yr expected annual loss, about once every 291 years
• TornadoRelatively Low$1.67M/yr expected annual loss, about once every 2 years
• Ice stormRelatively Low$63.7K/yr expected annual loss, about once every 1 year
• Strong windRelatively Low$412K/yr expected annual loss, about 4.3 events a year
• Cold waveRelatively Low$509K/yr expected annual loss, about 6.1 events a year
• Heat waveVery Low$153K/yr expected annual loss, about 5.6 events a year
• EarthquakeVery Low$14.97K/yr expected annual loss, about once every 1,852 years
• LightningVery Low$41.14K/yr expected annual loss, about 43 events a year
• Winter weatherVery Low$8,599/yr expected annual loss, about 14 events a year

Bars show the national percentile score (0 to 100) for each hazard. Dollar figures are expected annual losses to buildings, people and crops. Not rated here: avalanche, coastal flooding, hurricane, riverine flooding, tsunami, volcanic activity.

Check the flood zone for an address

Homes with flood insurance

29 of 4,740 (0.6%)

Homes in high-risk flood zones

0

Flood claims since 1978

30

Claims paid since 1978

$701K

• Hail119
• Thunderstorm Wind79
• Cold/Wind Chill42
• Winter Storm39
• High Wind26
• Tornado18 · 4 deaths
• Blizzard15
• Extreme Cold/Wind Chill12
• Flood12
• Flash Flood11

• TornadoEF3, 7.49 mi path, 440 yd wide06/12/2008

  Blencoe, Monona County

  4 deaths, 48 injured

  What happened

  This tornado tragically hit a boyscout camp north of Little Sioux Iowa killing 4 young scouts. The tornado initially touched down in Burt county Nebraska, crossed into Harrison county Iowa near mile marker 97 on Interstate 29, and then finally crossed into Monona county Iowa about 4 miles north of Little Sioux. In Monona county the tornado entered the Little Sioux Scout Ranch, destroying the rangers home near the entrance of the park giving it a rating of EF3. The storm then blew down trees and destroyed bunk houses at the camp. Four scouts were killed in one bunk house when a brick chimney collapsed on them. In total 48 people were injured at the camp. The tornado continued to topple trees as it tracked into Preparation Canyon State Park. Just before it entered the park a farmstead sustained damage. The tornado hit another farmstead about 2.5 miles southwest of Moorhead where trees were blown down and sheds damaged. The tornado then began to weaken and finally lifted about 2 miles southwest of Moorhead. The total path length was around 14 miles.

• Flood07/17/1996

  Monona

  $28.5M damage

  What happened

  The evening of July 16th thunderstorms produced a large area of 10 plus inches of rain from Monona County into Crawford County. Over half of Monona County averaged between 8 and 10 inches of rain. 12.75 inches of rain was reported at the Castana Experimental Farm. Extensive crop damage resulted across the county. Damage was also done to roads and bridges.

• TornadoEF3, 3.38 mi path, 1,200 yd wide04/10/2011

  Mapleton, Monona County

  14 injured

  What happened

  A tornado caused extensive damage in the Mapleton area with about 100 houses destroyed and many others severely damaged in a 12 to 15 block area on the southwest side of town. This caused the displacement of around 500 to 600 people. Most garages and stand alone structures were destroyed. In addition, large trees were uprooted and windows blown out of vehicles. Twelve to 14 people sustained minor injuries, the most severe a broken leg. The worst property damage was noted to be on the lower end of the EF3 category. The tornado started about 2 miles west southwest of Mapleton, moved into town, then turned north and ended 1 mile north of town. The path length was around 3.5 miles and the maximum width was around 3/4 of a mile.

• Dense Fog12/24/2025

  Monona

  1 death

  What happened

  Widespread dense fog reduced visibility to near 0 across Monona County. The Iowa State Patrol reported fog was present at a two-vehicle accident near the intersection of 130th Street and Walnut Avenue east of Mapleton at approximately 7:41 PM CST on December 25th. An eastbound vehicle attempted to turn around in the roadway and was struck by a second vehicle. The crash resulted in one fatality (indirect).

• Winter Weather02/14/2010

  Monona

  5 injured

  What happened

  Snow, mostly light, combined with northwest winds which increased to 25 to 35 mph. The strong winds and snow caused widespread blowing and drifting snow and poor visibilities beginning on 2/14. After a temporary break in the afternoon and early evening on the 14th, visibilities deteriorated again late in the evening into the morning of the 15th as light snow picked back up and the strong winds persisted. The visibilities occasionally dropped below 1/4 mile for an hour or two during the late morning of the 14th. Snowfall from the storm was only a couple of inches, but extensive snow cover already in place allowed the new snow to easily drift over roads and create the poor visibilities. Interstate 29 was closed across the county during the afternoon of the 14th after a 45 to 50 car pileup which caused several injuries. The Interstate remained closed into the morning hours of the 15th.

• Flood08/01/2011

  Albaton, Monona County

  $5M damage

  What happened

  Flooding along the Missouri River gradually worsened over Monona county during June and July as record releases from Gavins Point Dam brought widespread flooding along the river. Conditions improved markedly during August as releases were reduced and the river level at Decatur dropped below flood stage late in the month. Flooding in Monona county was mainly confined to agricultural lowlands, recreation areas and roads near the river. However, Blencoe started sandbag operations in June as did other businesses from Blencoe to Onawa. The flooding forced the post office in Blencoe to move operations to a nearby town. Late in June the Highway 175 bridge over the Missouri between Decatur and Onawa was closed due to erosion of the abutment on the Iowa side of the bridge and the bridge and highway remained closed through August. The Iowa Farm Bureau Federation estimated that the flood event caused total crop and economic losses of $32.3 million in Monona county.

• Heat07/25/2026

  Monona

• Heat06/29/2026

  Monona

• Thunderstorm Wind54 kt wind05/18/2026

  Ticonic, Monona County

• High Wind50 kt wind03/15/2026

  Monona

• Hail1.5" hail03/07/2026

  Blencoe, Monona County

• Extreme Cold/Wind Chill01/23/2026

  Monona

• High Wind50 kt wind01/21/2026

  Monona

• Dense Fog12/24/2025

  Monona

  1 death

• Onawa Municipal Water PlantServes 2,906 · Groundwater · Local governmentNo health violations
• Mapleton Municipal Water PlantServes 1,124 · Groundwater · Local governmentNo health violations+1 monitoring or reporting
• Whiting Water SupplyServes 727 · Groundwater · Local governmentNo health violations
• Ute Water SupplyServes 338 · Groundwater · Local governmentNo health violations+4 monitoring or reporting
• Blencoe Municipal WaterworksServes 224 · Groundwater · Local governmentNo health violations
• Moorhead Water SupplyServes 189 · Groundwater · Local governmentNo health violations+3 monitoring or reporting
• Soldier Water SupplyServes 180 · Groundwater · Local governmentNo health violations+6 monitoring or reporting
• Castana Municipal Water SupplyServes 103 · Groundwater · Local governmentNo health violations+2 monitoring or reporting