Clarke County, Iowa

What hazards hit Clarke County most?

The most frequent records are hail reports: 125 since 1960. 46% of its hail reports since 1960 fell in April and May. The rank column places the county among Iowa's counties by days with a record per 1,000 square miles of land over each hazard's complete period.

Source: NOAA NCEI Storm Events Database (county and forecast-zone records attributed to the county; a zone record shows its own totals on each county it covers). Days: dates with at least one record of the hazard in the county. Ranks: days with a record per 1,000 square miles of land (Census Bureau 2024 Gazetteer), since 1950 for tornadoes, 1955 for hail and thunderstorm wind, 1996 for the rest.

How many tornadoes has Clarke County had?

NOAA records 20 tornadoes in Clarke County from 1964 to 2024, the strongest rated EF2, with 0 deaths and 0 injuries recorded in the county. A tornado that crossed a county line is counted in each county it touched, with the length of its path inside the county.

Counted as whole tornadoes rather than county records, the Storm Prediction Center's database holds 21 tornadoes whose track touched Clarke County since 1950 (NOAA's county records number 20: they file a crossing tornado once per county segment, and the two databases differ on some tracks); along their whole tracks they killed 0 people.

Map of the strongest tornado tracks in Iowa.

Source: NOAA NCEI Storm Events Database, tornado records by county (path length in the county, maximum width); ratings as published: F scale before February 1, 2007, EF scale after. Whole-track figures: NOAA Storm Prediction Center tornado database (1950-2025). SPC severe weather database.

When was the last damaging storm in Clarke County?

The most recent record with damage, injuries or deaths is the May 6, 2024 tornado ($94,000 in damage in 2025 dollars).

This path was relayed by the Clarke County EMA with the tornado starting southwest of Woodburn just west of 310th Avenue. The tornado produced mainly tree damage southwest of Woodburn. Upon entering Woodburn near the intersection of Maple Street and Sigler Street, the tornado began producing damage to trees. The front wall of an older business in town collapsed although the building was in some disrepair. Additional tree and minor home damage occurred near the intersection of Walnut and Sherman Streets. More tree and powerline damage was noted along Smith Street on the east side of town before the tornado exited Woodburn. One final farmstead had outbuilding damage and tree branches downed before the tornado lifted.
National Weather Service event narrative, NOAA Storm Events Database (search the full record, event 1170122)

Source: NOAA NCEI Storm Events Database; every record of 2025-2026 is listed, earlier ones when they caused deaths, injuries or $250,000 of damage (2025 dollars), and every tornado.

The deadliest and costliest records

Source: NOAA NCEI Storm Events Database: deaths and injuries direct and indirect; damage is property plus crops as estimated by the National Weather Service, converted to 2025 dollars.

Is it getting more frequent?

Records per decade for Clarke County's most frequent hazards. Counts rose everywhere after 1996, when NOAA began recording every event type, so compare decades within a hazard's complete period only (the shaded cells come before it).

Source: NOAA NCEI Storm Events Database, records per calendar decade; zone records from the CZ_TYPE field (Z).

What time of year?

46% of its hail reports since 1960 fell in April and May. The two busiest months are in violet.

Source: NOAA NCEI Storm Events Database, records by the month they began.

Federal disaster declarations for Clarke County

FEMA's register lists 16 declarations that include Clarke County: 14 major disasters, 2 emergencies and 0 fire management assistance declarations. Most were for flood (6) and severe storm (4).

Source: FEMA OpenFEMA Disaster Declarations Summaries (v2), declarations through October 2, 2026; one declaration is counted once however many areas it names. OpenFEMA dataset page.

FEMA's modeled risk for Clarke County

FEMA's National Risk Index rates Clarke County Very Low overall, with an expected annual loss of $9.9 million. These are FEMA's model estimates of future loss from 18 hazards, not a count of what happened; they can differ from the record above.

Source: FEMA National Risk Index, county table, December 2025 release. FEMA's National Risk Index map.

Counties that share a border with Clarke County

1. Warren County 1,065
2. Madison County 585
3. Union County 570
4. Clarke County 549
5. Wayne County 493
6. Lucas County 490
7. Decatur County 476
8. Ringgold County 461

Source: U.S. Census Bureau county adjacency file; NOAA NCEI Storm Events Database, records since 1950. The Census Bureau's adjacency file.

Next

• Tornadoes in IowaEvery Iowa tornado since 1950 and the counties with the most per square mile
• Hail in IowaThe state's hail reports, by county, year and month
• The Iowa recordEvery hazard in the state, its deadliest events and its federal declarations
• FEMA's risk rating for each hazard in Clarke CountyThe hazard risk calculator: 18 hazards beside the county's record
• Download Clarke County's FEMA declarations (CSV)16 rows: every declaration that named the county, for your own analysis