Grundy County

Every recorded tornado

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

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.

More event types since 1996

Costliest events since 1996

1. Aug 1, 2003Drought, Grundy$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. Jun 8, 1999Flash Flood$500,000
   National Weather Service narrative

   A strong upper level disturbance moved north-northeast into Iowa during the afternoon hours. A very unstable airmass was in place over the state with lifted indices near -10 degrees C. Surface dew points were in the low 70s as high temperatures soared into the upper 80s and 90s. This combined to produce CAPE values near 5000 J/kg. Thunderstorms erupted initially developed in more or less an east to west line. That line lifted north and as it did produced very heavy rain and some hail of three quarters of an inch to an inch in diameter. A second line formed in a more north to south orientation and moved east across the state. There were also some reports of dime size or larger hail…

3. Jun 20, 1997Thunderstorm Wind$500,000
4. May 29, 2013Flash Flood$450,000
   National Weather Service narrative

   Many county roads closed due to flooding.

5. Nov 10, 1998High Wind, Grundy$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. May 25, 2008Tornado$300,000
   National Weather Service narrative

   This was the initial tornado touchdown point. The tornado continued on into Butler County.

7. Aug 9, 2009Hail$250,000
   National Weather Service narrative

   A very warm, moist, and unstable airmass was in place over Iowa from 8th into the 9th. Surface temperatures on the 8th warmed into the upper 80s and 90s, with dew point readings in the 70s. A weak cold front moved into the state during the evening of the 8th and early morning of the 9th. There was little thunderstorm development initially as the airmass was capped. Temperatures at the 700 mb level were +14 to +17 C. During the early morning hours of the 9th, a short wave lifted northeast out of the southern Rockies. This resulted in cooling of the mid levels of the atmosphere, thus destabilizing the airmass. The cold front stall out during the morning of the 9th as a second short…

8. May 29, 2013Flood$250,000
   National Weather Service narrative

   Still reporting major flooding throughout the county with many county roads and some city streets closed due to flooding. Highway 14 south of Grundy Center is closed as is the Highway 20 exit at Wellsburg.

9. Aug 9, 2009Thunderstorm Wind$250,000
   National Weather Service narrative

   Grain bins and metal outbuildings were destroyed by high wind.

10. Feb 24, 2007Winter Storm, Grundy$250,000
    National Weather Service narrative

    A major winter storm affected Iowa through the 24th and 25th of February. A powerful upper low moved onto the west coast during the middle of the week, and advanced east through the Rockies during the end of the week. Strong warm air advection took place over the top of a shallow polar airmass that was in place over Iowa. The east-southeasterly flow at the surface drew cool and dry air into the state from the east, setting the stage for a significant ice storm. The main area of precipitation overspread the state during the early morning hours of the 24th and persisted through much of the 25th. Initially, very warm air aloft meant that the precipitation fell in the form of freezing…

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 18, 1936

All-time low

−34°FFeb 13, 1905

Warmest night

85°FJul 24, 1912

Coldest day

−16°FFeb 3, 1996

Wettest day

6.25 inJul 10, 2000

Snowiest day

15.0 inJan 1, 1942

Hottest year

1931mean 52.3°F

Coldest year

1893mean 42.8°F

Wettest year

192452.18 in

Driest year

198818.95 in

Snowiest season

60.6 in1972-73

Station Grundy Center (USC00133487), 985 ft elevation, 1.3 miles from the population centre. Daily records from 1893 to October 27, 2026; 97.8% 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 USC00133487.
• 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.