Polk County

Every recorded tornado

1. Injuries and deaths are for the tornado’s whole path, which may extend beyond the county. Deaths recorded within Polk County: 2.
2. Weak tornadoes were under-recorded before Doppler radar coverage became national in the early 1990s, so earlier decades read low. Ratings use the Fujita scale before February 2007 and the Enhanced Fujita scale after.

Storm Prediction Center severe weather database, 1950 to 2025.

Smoke overhead

1. A smoke day is a date on which a smoke plume traced by NOAA Hazard Mapping System analysts from satellite imagery covered this place's point (the county's population centre or the city centre). Counts here are of medium or heavy smoke. Since 2018 analysts have often drawn light smoke as one area over most of the continent, so light-smoke counts are not comparable from year to year. The plumes show smoke anywhere in the air above, not air quality at the ground, and smoke hidden by cloud is missed.

NOAA Hazard Mapping System smoke analysis, 2011 to 2026, retrieved October 30, 2026.

Claims by ZIP code

This product uses the Federal Emergency Management Agency's OpenFEMA API, but is not endorsed by FEMA. The Federal Government or FEMA cannot vouch for the data or analyses derived from these data after the data have been retrieved from the Agency's website(s).

OpenFEMA NFIP Redacted Claims v3, refreshed August 4, 2026. NOAA Storm Events through 2026.

River crests

River gauges

1. Crests are the highest and the recent crests the National Weather Service lists for each river gauge in the county that has a flood stage, not every flood. Flood categories use each gauge's current flood stages; crests from before levees, dams or channel changes may not be comparable. Crests measured on an old datum are left out of the rankings.

NOAA National Water Prediction Service gauge records, retrieved October 30, 2026.

1. The Palmer Drought Severity Index is computed by NOAA each month from the county's average temperature and precipitation, relative to the county's own climate. Zero is normal; -3 or lower is severe drought and -4 or lower extreme drought. It describes the long-term balance of moisture, not water supply or crop losses.

NOAA NCEI nClimDiv county Palmer Drought Severity Index, 1895 to September 2026, issued October 6, 2026.

Mapped landslides

Mapped by NASA (1).

1. Landslides mapped in the USGS compilation of landslide inventories across the United States (version 3.0, 2025), rated probable or better. The compilation joins inventories made by federal and state agencies for different purposes and areas, so the number mapped in a county reflects how closely it has been surveyed as much as how often its slopes fail. An area with few records may simply not have been mapped. Deaths are as recorded in the inventories; a slide listed in two inventories is counted once.

USGS Landslide Inventories across the United States, version 3.0, retrieved October 27, 2026.

More event types since 1996

Costliest events since 1996

1. Mar 5, 2022Tornado$75.0 million
   National Weather Service narrative

   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.

2. Jun 29, 1998Thunderstorm Wind$40.0 million
   National Weather Service narrative

   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…

3. Aug 1, 2003Drought, Polk$12.7 million
   National Weather Service narrative

   Dry weather settled in over Iowa during the month. The last widespread rain occurred on 09 July. With the increasingly dry conditions became a primary concern as the month progressed. An extended period of heat and humidity from the 15th to 25th saw highs into the 90s to over 100 degrees F. in some locations. By month's end drought indices had worsened to severe to extreme drought across south central Iowa and at least moderate drought over the remainder of the HSA. Waterloo had its driest August on record, Des Moines its 3rd driest and Ottumwa its 8th driest. A cold front brought only a brief respite from the intense heat, as temperatures rebounded into the 90s to near 100…

4. Jun 29, 1998Tornado$10.0 million
   National Weather Service narrative

   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…

5. Jun 29, 1998Thunderstorm Wind$10.0 million
   National Weather Service narrative

   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…

6. Jun 12, 2001Hail$9.5 million
   National Weather Service narrative

   The supercell that moved across northern Iowa during the early morning hours left behind a strong outflow boundary. This outflow boundary became established east to west across central Iowa. At the same time a complex of thunderstorms that was generated by a short wave moving across Nebraska advanced toward western Iowa just before sunrise. Though upper level jet divergence was in place, a strong mid level cap was in place through most of the night and the outflow boundary never produced any thunderstorm activity. Temperatures in the mid levels fall significantly around sunrise. The outflow boundary "lit up like a Christmas tree" around sunrise. The thunderstorms became severe…

7. Jun 14, 2008Flash Flood$7.0 million
   National Weather Service narrative

   Very high water along the Des Moines River continued to put stress on the levee system in Des Moines. The crest had passed, however water levels were still within about a foot of the record crest. A weak spot in the levee in the Birdland Park area gave way in spite of the heroic effort put forth by the citizens and the National Guard to shore the levee up. A breech of about 100 feet in width occurred around 0230 CST. This caused very rapid water rises of about 4 feet in the flooded area within an hour, and about 8 feet within several hours. A mandatory evacuation order was given by the Des Moines Police. About 271 homes were affected by the flooding. The flooding continued after…

8. Jun 1, 2008Flood$6.0 million
   National Weather Service narrative

   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.

9. Jun 18, 1998Flood, Polk$6.0 million
   National Weather Service narrative

   Following a brief break from the rain on the 16th, rainfall resumed on the 17th and 18th. Heavy rain fell over just about the entire state on both days, with the heaviest amounts of 1 to 3 inches on the first night in the Nishnabotna River basin, the Upper Des Moines and Iowa basins, and the lower parts of the South Skunk basin. These rains fell on already saturated soils and resulted on considerable runoff. On the 18th, the Des Moines metropolitan area was blitzed with a massive flooding event. Local rains in the city ranged form 1 to 4 inches, much of it falling in one to two hours. Much of this water was quickly added to the flows on the already high Raccoon River. The Raccoon…

10. May 21, 2024Tornado$5.2 million
    National Weather Service narrative

    This was a long track tornado which started just to the southwest of the Johnston High School with fascia and soffit damage to houses along Catalina Drive. The tornado blew windows out of the high school and continued to produce tree and minor roof damage through the Ashton Point neighborhood. The tornado crossed Camp Dodge and blew down a tree along NW Beaver Drive before crossing Saylorville Reservoir. The tornadoes path took it between Polk City and Ankeny with EF0 damage to trees and houses along Highway 415 and NW 44th Street. The damage began to intensify as the tornado moved northeast with EF1 damage becoming more prevelent in neighborhoods south of Alleman. The first EF2…

1. Storm Events records before 1996 cover only tornadoes, thunderstorm wind and hail. Damage figures are as reported by the National Weather Service at the time, not adjusted for inflation.

NOAA NCEI Storm Events Database, 1950 to 2026, issued October 26, 2026.

All-time high

108°FAug 16, 1983

All-time low

−26°FFeb 3, 1996

Warmest night

81°F3 times, most recently Jul 27, 2026

Coldest day

−12°FDec 24, 1983

Wettest day

6.18 inAug 27, 1975

Snowiest day

13.7 inJan 26, 1996

Hottest year

2012mean 56.1°F

Coldest year

1951mean 46.9°F

Wettest year

199355.88 in

Driest year

195617.07 in

Snowiest season

69.0 in2009-10

Station Des Moines International Airport (USW00014933), 939 ft elevation, 6.7 miles from the population centre. Daily records from 1945 to October 26, 2026; 100.0% of days in the last 30 years are complete. Records at a single station can differ from a city’s official threaded record, which may combine several stations.

NOAA NCEI Global Historical Climatology Network Daily.

This product uses the Federal Emergency Management Agency's OpenFEMA API, but is not endorsed by FEMA. The Federal Government or FEMA cannot vouch for the data or analyses derived from these data after the data have been retrieved from the Agency's website(s).

OpenFEMA Disaster Declarations Summaries, retrieved October 30, 2026. Statewide declarations are not listed.

Neighbouring counties

• Tornadoes NOAA Storm Prediction Center severe weather database, through 2025.
• Tropical cyclones NOAA National Hurricane Center HURDAT2 (Atlantic; Northeast and Central Pacific), through 2025.
• Wildfire USGS/USFS Monitoring Trends in Burn Severity, through 2026.
• Storm events NOAA NCEI Storm Events Database, through 2026.
• Flood insurance OpenFEMA NFIP Redacted Claims v3, refreshed August 4, 2026.
• Declarations OpenFEMA Disaster Declarations Summaries v2, retrieved October 30, 2026.
• Weather records NOAA NCEI Global Historical Climatology Network Daily, station USW00014933.
• River crests NOAA National Weather Service, National Water Prediction Service river gauges, retrieved October 30, 2026.
• Drought NOAA NCEI nClimDiv county Palmer Drought Severity Index, through September 2026.
• Smoke NOAA NESDIS Hazard Mapping System smoke analysis, retrieved October 30, 2026.
• Landslides USGS Landslide Inventories across the United States, version 3.0 (2025).
• Earthquakes USGS ANSS Comprehensive Earthquake Catalog (ComCat), retrieved October 30, 2026.

Joins, thresholds and known limits are set out in the methodology. Found an error? Report it. Page built October 30, 2026.