Decatur County

Every recorded tornado

1. Injuries and deaths are for the tornado’s whole path, which may extend beyond the county. Deaths recorded within Decatur County: 0.
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.

1. Earthquakes of magnitude 2.5 or more in the USGS Comprehensive Catalog since 1900. Within 50 miles means the epicentre lies within 50 miles of the county boundary (or inside the county).
2. Small earthquakes were under-recorded before the modern seismic networks of the 1970s and are still missed in remote areas, so early decades read low. Magnitudes are as the catalogue reports them and mix scales (moment, local and body-wave).

USGS ANSS Comprehensive Earthquake Catalog, 1900 to present, retrieved October 30, 2026.

More event types since 1996

Costliest events since 1996

1. Aug 1, 2003Drought, Decatur$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…

2. Oct 26, 1997Heavy Snow, Decatur$640,000
   National Weather Service narrative

   The first major winter storm of the season developed over the central Rockies as a powerful upper level jet stream dove into the southern Rockies. Intense low pressure developed over northern Oklahoma, then drifted northeast on the early morning of the 26th. A cold high pressure of Arctic origin was poised to the north of Iowa. The high gradually pushed cold air south into the central U.S. causing the precipitation on the northwest edge of the storm system to change to snow. During the early morning hours, the system went convective with widespread "thundersnow" reported over the south half of Iowa. Lightning struck a tree outside of a house in Nevada causing damage to electrical…

3. Mar 5, 2022Tornado$500,000
   National Weather Service narrative

   This tornado passed through three counties including Decatur, Wayne and Lucas. The tornado developed east of Leon in central Decatur county and headed northeast. The torndo remained in rural areas of the county for the duration of its path. Damage was primarily to broken power poles, although residential house damage was also noted. A roof was removed from a house just east of Garden Grove producing EF2 damage with other damage to nearby outbuildings also noted. The tornado exited into Wayne county just north of 140th Street.

4. Jun 3, 2014Flash Flood$400,000
   National Weather Service narrative

   Water of 2 feet to 3 feet deep in some places was reported in Davis City as the drainage system could not keep up with the rain.

5. Nov 10, 1998High Wind, Decatur$300,000
   National Weather Service narrative

   Iowa experienced the worst November storm system since the great storm of 9 and 10 November 1975. During the 9th, low pressure developed over southeast Colorado. The low moved across Kansas during the afternoon and evening of the 9th and deepened to about 990 mb. Warm and moist air was drawn north ahead of the low resulting in widespread across the state. Thunderstorms erupted during the late evening of the 9th, though no severe weather occurred. During the predawn hours of the 10th, a jet streak rotated around the base of the upper level low pressure area. The jet stream, combined with a tropospheric fold, resulted in explosive deepening of the low. As the low moved through…

6. Jun 5, 2010Flood$250,000
   National Weather Service narrative

   A weak cold front moved southeast across Iowa early on the 4th and had become stationary east-west to the south of the state. The thermal gradient increased during the day and moisture pooled along the front by evening. The atmosphere became quite unstable by late afternoon with temperatures reaching well into the 90s south of the front, and dew point readings rising into the low 70s along the front. CAPE was in the 3000 to 4000 J/kg range by mid to late evening with lifted indices in the -5 to -10 C range. Precipitable water values increased to near 2 inches along the front as the 850 mb jet increased to 30 to 40 kts. Downdraft CAPE was in the 700 to 1000 J/kg range and available…

7. Aug 23, 2007Flash Flood$200,000
   National Weather Service narrative

   Water was reported over the road at J20 and 340th Avenue near the Wayne County line.

8. Jun 19, 2011Thunderstorm Wind$200,000
   National Weather Service narrative

   Significant tree damage in the town of Leon. An estimated 100 to 200 trees felled in town with large trees littering the town. Trees fell on the roofs of many houses, but no major structural damage.

9. Jun 3, 2014Flash Flood$150,000
   National Weather Service narrative

   The Decatur County Engineer reported an estimated 25 culverts damaged and 12 bridges damaged from water. Another 40 locations of roadway were overtopped by water resulting in at least 20 road closures.

10. May 22, 1998Thunderstorm Wind$150,000
    National Weather Service narrative

    A second round of thunderstorms moved into Iowa during the early morning hours. A mesoscale convective system developed in Nebraska north of a stationary frontal boundary and raced east into Iowa. The storms weakened as the moved to the east, but were able to drop one inch diameter hail in Adair County at Greenfield and produced winds around 80 MPH in Taylor County at Lenox, and 73 MPH winds at Greenfield in Adair County. The winds in Lenox caused about $150,000 damage to a farm supply building there. A 30 square foot section of the roof was damaged and a large entrance door on the building was torn off. The storms moved east during the night and produced high winds in Ringgold…

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

113°FAug 9, 1934

All-time low

−29°FJan 12, 1912

Warmest night

85°FJul 25, 1936

Coldest day

−11°F2 times, most recently Dec 24, 1983

Wettest day

6.38 inSep 12, 1949

Snowiest day

18.0 inJan 25, 1898

Hottest year

2012mean 54.8°F

Coldest year

1917mean 46.5°F

Wettest year

199358.58 in

Driest year

198816.28 in

Snowiest season

68.4 in2009-10

Station Lamoni (USC00134585), 1,128 ft elevation, 8.7 miles from the population centre. Daily records from 1897 to October 26, 2026; 99.1% 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 USC00134585.
• 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.
• 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.