Polk County, IA Environment & Hazard Risk

• Strong windVery High$11.49M/yr expected annual loss, about 6.0 events a year
• TornadoRelatively High$30.95M/yr expected annual loss, about once every 2 years
• HailRelatively High$7.39M/yr expected annual loss, about 6.1 events a year
• Heat waveRelatively High$10.71M/yr expected annual loss, about 7.3 events a year
• DroughtRelatively High$3.07M/yr expected annual loss, about 6.5 events a year
• Ice stormRelatively High$1.36M/yr expected annual loss, about once every 1 year
• Cold waveRelatively High$9.77M/yr expected annual loss, about 6.0 events a year
• Winter weatherRelatively High$506K/yr expected annual loss, about 14 events a year
• LightningRelatively Moderate$816K/yr expected annual loss, about 44 events a year
• LandslideRelatively Low$6,139/yr expected annual loss, about once every 8 years
• EarthquakeRelatively Low$820K/yr expected annual loss, about once every 1,647 years
• WildfireVery Low$90.75K/yr expected annual loss, about once every 3,822 years
• HurricaneVery Low$14.29K/yr expected annual loss, about once every 101 years

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, riverine flooding, tsunami, volcanic activity.

Check the flood zone for an address

Homes with flood insurance

670 of 163,854 (0.4%)

Homes in high-risk flood zones

1,607

Insured in high-risk zones

366 (23%)

Flood claims since 1978

1,550

Claims paid since 1978

$38.52M

• Thunderstorm Wind620 · 1 death
• Hail583
• Heavy Rain350
• Flood177
• Flash Flood118 · 3 deaths
• Lightning42
• High Wind39
• Tornado36
• Drought32
• Winter Storm31 · 1 death

• TornadoF2, 18.3 mi path, 150 yd wide06/29/1998

  Grimes, Polk County

  83 injured, $10.07M damage

  What happened

  A complex weather situation was set up over the central U.S. as a mesoscale convective system passed to the south of Iowa during the overnight hours and early morning of the 29th. Initially, the surface warm front was located to the south of this system. That was not actually the case aloft however. During the predawn hours the surface front surged north and by sunrise was located across northeast Nebraska across northern Iowa. The airmass was very unstable to the south of the front with dew point temperatures will in the 70s F. The initial development of thunderstorms took place during the early part of the day over northeast Nebraska. The storms became severe quickly as they moved and developed eastward into Iowa. By mid morning, the storms had formed a nearly east to west line. Storm relative inflow into the line was around 40 knots. The storms produced a variety of severe weather across Iowa. They initially moved east across the northern and central counties, but then began sinking sinking southeast. The dominant severe weather with the storms was extremely high winds. Damage was very widespread across the state. Winds in excess of 100 MPH were reported with...

• Thunderstorm Wind104 kt wind06/29/1998

  Des Moines, Polk County

  40 injured, $40M damage

  What happened

  A complex weather situation was set up over the central U.S. as a mesoscale convective system passed to the south of Iowa during the overnight hours and early morning of the 29th. Initially, the surface warm front was located to the south of this system. That was not actually the case aloft however. During the predawn hours the surface front surged north and by sunrise was located across northeast Nebraska across northern Iowa. The airmass was very unstable to the south of the front with dew point temperatures will in the 70s F. The initial development of thunderstorms took place during the early part of the day over northeast Nebraska. The storms became severe quickly as they moved and developed eastward into Iowa. By mid morning, the storms had formed a nearly east to west line. Storm relative inflow into the line was around 40 knots. The storms produced a variety of severe weather across Iowa. They initially moved east across the northern and central counties, but then began sinking sinking southeast. The dominant severe weather with the storms was extremely high winds. Damage was very widespread across the state. Winds in excess of 100 MPH were reported with...

• TornadoEF2, 13.62 mi path, 400 yd wide03/06/2022

  Avon, Polk County

  $75M damage

  What happened

  This tornado passed from Warren county into Polk county near the intersection of Highway 69 and County Line Road. The tornado crossed E Pine Avenue removing the roof of a house and then clipped the north edge of Avon producing EF2 damage to a couple of houses. The tornado then crossed the Des Moines River and impacted the Woodland Hills neighborhood damaging muliple structures. The damage continued to the northeast into less inhabited areas of eastern Polk county, however the tornado remained strong with EF2 damage at several locations along its path. The tornado crossed University Avenue near its intersection with NE 112th Street and then exited the county into Jasper county.

• Flood06/01/2008

  Pleasant Hill, Polk County

  $50.1M damage

  What happened

  Iowa came off of a very wet May, only to be followed by a near record wet June. Some of the flooding along Iowa's rivers continued from May into June. Heavy rains fell on a nearly daily basis somewhere in Iowa through the first half of the month. The first series of heavy rain events caused flooding over a large part of Iowa. Some of the flooding began as flash flooding, then transitioned into general river flooding. A considerable amount of agricultural land was put under water due to the extensive river flooding. This began what would be a catastrophic loss in agricultural production.

• Drought07/01/2012

  Polk

  $45M damage

  What happened

  Very warm and dry weather that began in the spring continued into the summer. Temperatures warmed sharply the last few days of June. The heat persisted into July. Temperatures for the month of July were among the warmest on record. In Des Moines, the monthly mean temperature was the second highest of record, only eclipsed by July of 1936. Rainfall was in short supply across the state. Much of the state recorded less than 50% of normal rainfall for the month, with a few locations under 10% of normal. In addition, extended periods of temperatures above 95 F resulted in problems with pollination of the crops. Rapid deterioration of the corn and soybean crop took place with several periods of temperatures in excess of 100 degrees. By the end of the month, officials estimated that 20% of the crop yield had been lost to the drought. At the current price, the loss total was in excess of $2.25 billion. As of 31 July, the USDA reported that Secretarial Primary Drought Designations had been listed for 21 counties in the Des Moines CWA, with 11 receiving Contiguous Designation. The primary counties were Butler, Bremer, Hamilton, Hardin, Grundy, Black Hawk, Boone, Story,...

• Drought08/01/2013

  Polk

  $21M damage

  What happened

  Serious drought conditions gripped the state through the summer months. Initial sub-soil moisture was good at the beginning of the growing season. The recharged soil was sufficient to maintain the crops through a good part of the summer. Rainfall remained low through August as well and crops deteriorated rapidly under the warmer than normal and very dry conditions. Rainfall for the summer was between 1/3 and 2/3rds of normal across much of the Des Moines CWA. A large part of the CWA received under 5% of normal rainfall in August, with most areas under 20%. Crop loss through the month was around 10%. This translated to over $600 million in crop loss for the corn crop, and about $350 million for soybeans.

• Heavy Snow02/20/2026

  Polk

• Thunderstorm Wind56 kt wind07/30/2025

  Capitol Hgts, Polk County

  $50K damage

• Thunderstorm Wind50 kt wind07/28/2025

  Urbandale, Polk County

  $1,500 damage

• Thunderstorm Wind55 kt wind07/24/2025

  Bondurant, Polk County

  $7,000 damage

• Thunderstorm Wind53 kt wind07/24/2025

  Elkhart, Polk County

• Flash Flood07/21/2025

  Ashawa, Polk County

  $20K damage

• Thunderstorm Wind58 kt wind07/11/2025

  Elkhart, Polk County

• Thunderstorm Wind61 kt wind07/11/2025

  Altoona, Polk County

• Des Moines Water WorksServes 246,055 · Purchased surface water · Local governmentNo health violations
• Ankeny, City ofServes 76,207 · Purchased surface water · Local governmentNo health violations
• West Des Moines Water WorksServes 73,959 · Purchased surface water · Local governmentNo health violations
• Urbandale Water UtilityServes 45,605 · Purchased surface water · Local governmentNo health violations
• Johnston Municipal Water SupplyServes 24,897 · Purchased surface water · Local governmentNo health violations
• Altoona Water SupplyServes 22,436 · Groundwater · Local government1 health violation+2 monitoring or reporting
• Clive Water DepartmentServes 20,277 · Purchased surface water · Local governmentNo health violations
• Grimes Water SupplyServes 17,997 · Groundwater · Local governmentNo health violations