Grundy County, Iowa tornadoes

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40confirmed tornadoes since NOAA records began in 1950 (the first here in 1960). Most recent: August 18, 2025, EFU. 2026 so far: 0 preliminary reports preliminary

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Map

Every tornado path in the county

Tornado paths, 1950 to 2025
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(E)F0(E)F1(E)F2(E)F3(E)F4(E)F5Unrated

Each path is a straight line from where the tornado started to where it ended, which is all most NOAA records hold. Tap a path for its details.

Recent warnings

Recent warnings in Grundy County

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The record

At a glance

Total401950 to 2025
Per year0.5average since 1950
Peak monthMay14 of 40
StrongestEF5May 25, 2008
Deaths10whole paths, see note
Injuries78whole paths, see note

Deaths and injuries are NOAA's totals for each tornado's whole path, which can extend beyond Grundy County.

Seasons

When tornadoes hit here

By month

140 Jan: 0Feb: 0Mar: 3Apr: 3May: 14Jun: 5Jul: 7Aug: 4Sep: 0Oct: 1Nov: 3Dec: 0JanFebMarAprMayJunJulAugSepOctNovDec

May is the peak month, with 14 of 40 tornadoes.

By time of day

70 12 AM: 2: 0: 03 AM: 0: 0: 06 AM: 3: 0: 09 AM: 0: 0: 012 PM: 0: 4: 33 PM: 5: 5: 66 PM: 7: 3: 29 PM: 0: 0: 012 AM3 AM6 AM9 AM12 PM3 PM6 PM9 PM

Most often around 6:00 PM. Times as recorded by NOAA, mostly Central Standard Time.

By year, 1950 to 2025

50 1950: 0: 0: 0: 0: 0: 0: 0: 0: 0: 01960: 1: 0: 0: 0: 0: 0: 2: 0: 0: 01970: 0: 2: 0: 1: 0: 1: 0: 1: 1: 01980: 0: 0: 0: 0: 0: 0: 0: 1: 0: 11990: 1: 1: 0: 0: 0: 0: 0: 0: 0: 12000: 1: 3: 1: 0: 5: 0: 0: 0: 2: 32010: 0: 0: 0: 0: 4: 0: 2: 0: 0: 02020: 0: 0: 0: 2: 0: 319501960197019801990200020102020

The line is the five-year average. Tornadoes before about 1953 were under-reported, and better radar since the 1990s finds more weak ones.

By rating

EF0
12
EF1
16
EF2
6
EF3
1
EF4
1
EF5
1
Unknown
3

Ratings before February 2007 use the original F scale; the numbers line up with today's EF scale. Unknown means NOAA could not assign a rating.

The record

Notable tornadoes

Deadliest

EF5, May 25, 2008

9 deaths, 70 injuries Strongest

EF5, May 25, 2008

40.97 mile path Longest path

40.97 miles, EF5

May 25, 2008, whole path Widest

2,100 yards, EF5

May 25, 2008
Every tornado

All 40 tornadoes, newest first

DateRatingPath lengthWidthDeathsInjuries
Aug 18, 2025EFU0.62 mi35 yd00
Aug 18, 2025EFU4.53 mi50 yd00
Aug 18, 2025EFU1.39 mi50 yd00
Mar 31, 2023EF13.53 mi80 yd00
Mar 31, 2023EF14.14 mi80 yd00
Nov 28, 2016EF01.47 mi25 yd00
Nov 28, 2016EF05.68 mi50 yd00
Aug 31, 2014EF01.63 mi75 yd00
Jul 6, 2014EF01.47 mi20 yd00
Jul 6, 2014EF13.21 mi100 yd00
Jun 29, 2014EF11.9 mi50 yd00
Jun 21, 2009EF12.08 mi70 yd00
Jun 21, 2009EF12.3 mi90 yd00
Jun 21, 2009EF00.37 mi30 yd00
May 25, 2008EF01.07 mi50 yd00
May 25, 2008EF540.97 mi2,100 yd970
May 21, 2004F00.5 mi40 yd00
May 21, 2004F00.5 mi40 yd00
May 21, 2004F00.5 mi30 yd00
May 21, 2004F13.5 mi100 yd00
May 21, 2004F03 mi50 yd00
Apr 18, 2002F00.2 mi30 yd00
May 10, 2001F11 mi100 yd00
May 10, 2001F28 mi875 yd00
May 10, 2001F21.7 mi200 yd00
Nearby

Nearby counties

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Source: NOAA Storm Prediction Center severe weather database, 1950 to 2025, and SPC preliminary reports for 2026. Page built October 13, 2026.