O'Brien County, Iowa tornadoes

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37 confirmed tornadoes since NOAA records began in 1950 (the first here in 1951). Most recent: July 20, 2024, EFU. 2026 so far: 1 preliminary report preliminary

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Every tornado path in the county

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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.

At a glance

Total371950 to 2025
Per year0.5average since 1950
Peak monthJune15 of 37
StrongestF3May 5, 1964
Deaths0whole paths, see note
Injuries9whole paths, see note

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

When tornadoes hit here

By month

150 Jan: 0Feb: 0Mar: 0Apr: 4May: 9Jun: 15Jul: 5Aug: 0Sep: 0Oct: 3Nov: 0Dec: 1JanFebMarAprMayJunJulAugSepOctNovDec

June is the peak month, with 15 of 37 tornadoes.

By time of day

110 12 AM: 0: 0: 03 AM: 0: 0: 06 AM: 0: 0: 09 AM: 0: 0: 012 PM: 1: 2: 23 PM: 3: 6: 116 PM: 4: 2: 19 PM: 2: 3: 012 AM3 AM6 AM9 AM12 PM3 PM6 PM9 PM

Most often around 5:00 PM. Times as recorded by NOAA, mostly Central Standard Time.

By year, 1950 to 2025

40 1950: 0: 1: 0: 0: 0: 0: 0: 0: 0: 01960: 0: 0: 0: 1: 1: 1: 0: 0: 1: 11970: 0: 2: 0: 1: 0: 0: 0: 0: 0: 01980: 1: 0: 0: 0: 1: 0: 2: 0: 0: 01990: 0: 0: 0: 2: 0: 0: 0: 0: 0: 12000: 1: 3: 1: 0: 1: 1: 0: 0: 4: 02010: 4: 0: 1: 0: 1: 1: 0: 0: 0: 02020: 0: 1: 0: 0: 2: 019501960197019801990200020102020

The line is the five-year average. Tornadoes before about 1953 were under-reported, and better radar since the 1990s finds more weak ones. This year so far: 1 preliminary reports.

By rating

EF0
18
EF1
11
EF2
4
EF3
3
Unknown
1

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.

Notable tornadoes

Strongest

F3, May 5, 1964

67 mile path Longest path

67 miles, F3

May 5, 1964, whole path Widest

300 yards, F3

May 5, 1964

All 37 tornadoes, newest first

DateRatingPath lengthWidthDeathsInjuries
Jul 20, 2024EFU0.62 mi25 yd00
May 31, 2024EF00.95 mi75 yd00
Dec 15, 2021EF13.85 mi100 yd00
Oct 23, 2015EF00.17 mi50 yd00
May 11, 2014EF00.49 mi50 yd00
May 4, 2012EF00.5 mi50 yd00
Jun 25, 2010EF13.27 mi100 yd00
Jun 25, 2010EF00.58 mi200 yd00
Jun 22, 2010EF00.06 mi50 yd00
Jun 1, 2010EF00.3 mi50 yd00
Jun 11, 2008EF10.86 mi50 yd00
Jun 11, 2008EF25.73 mi300 yd00
Jun 11, 2008EF00.86 mi50 yd00
May 1, 2008EF00.1 mi50 yd00
May 18, 2005F00.1 mi50 yd00
May 9, 2004F00.2 mi50 yd00
Jun 7, 2002F00.1 mi50 yd00
Jun 13, 2001F17 mi200 yd00
Apr 30, 2001F03 mi100 yd00
Apr 30, 2001F03 mi100 yd00
Jul 9, 2000F10.5 mi100 yd00
Jun 5, 1999F02.2 mi50 yd00
Jun 7, 1993F00.5 mi23 yd00
Jun 7, 1993F11.8 mi67 yd00
Jul 28, 1986F10.1 mi13 yd00

2026 preliminary reports not yet confirmed

Report dateLocationRating
Apr 13, 20262 NE ArcherNot yet rated

Preliminary reports from the Storm Prediction Center. One tornado can be reported more than once, and NOAA confirms the final record months later.

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 12, 2026.