Bon Homme County, South Dakota

What hazards hit Bon Homme County most?

The most frequent records are hail reports: 229 since 1960. 48% of its hail reports since 1960 fell in July and August. The rank column places the county among South Dakota'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 Bon Homme County had?

NOAA records 26 tornadoes in Bon Homme County from 1954 to 2023, the strongest rated F3, with 0 deaths and 2 injuries recorded in the county. That is 11th of 66 South Dakota counties by days with tornadoes per 1,000 square miles since 1950. 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 26 tornadoes whose track touched Bon Homme County since 1950 (NOAA's county records number 26, the same count); along their whole tracks they killed 0 people.

Map of the strongest tornado tracks in South Dakota.

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 Bon Homme County?

The most recent record with damage, injuries or deaths is the June 21, 2024 flood ($1.1 million in damage in 2025 dollars).

Rainfall amounts across Bon Homme County from June 20-22 ranged from 2 to 3 inches with an estimated 5 to 6 inches across the far northern portion of the county. Overland flooding ensued with additional major flooding along the James River. One home experienced a partial basement collapse and 3 businesses received flood damage. During peak flooding on June 21, water was overflowing at least 60 roads county-wide with the worst impacts north of South Dakota Highway 46, including South Dakota Highway 25 and the intersection of South Dakota Highways 46 and 37. Water also overran South Dakota Highway 50 near the Bon Homme Golf Course. Preliminary damage assessments estimate loss to public infrastructure across the county to be nearly 1.17 million dollars. The majority of overland flooding subsided by June 22, but river flooding continued through the end of the month. …
National Weather Service event narrative, NOAA Storm Events Database (search the full record, event 1193386)

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

A damage figure marked "step" is a record from before 1993: NOAA then filed damage by category, and the figure is the category as entered, in the dollars of that year, not an estimate of the loss.

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 Bon Homme 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).

Drought in the 2020-26: 40 records against 12 in the decade before, 40 of them forecast-zone records. High wind and dust storms in the 2020-26: 24 records against 7 in the decade before, 24 of them forecast-zone records. Cells marked z rose mostly through zone records. The local National Weather Service office files these once per forecast zone, so a change in how it draws its zones or splits a storm into records moves this count as much as the weather does; read it beside the Bon Homme County days with a record above.

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

What time of year?

48% of its hail reports since 1960 fell in July and August. The two busiest months are in violet.

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

Federal disaster declarations for Bon Homme County

FEMA's register lists 16 declarations that include Bon Homme County: 13 major disasters, 3 emergencies and 0 fire management assistance declarations. Most were for severe storm (6) and flood (5).

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.

How many floods has Bon Homme County had?

NOAA's Storm Events Database holds 107 flood or flash flood records for Bon Homme County from 1997 to 2024, on 72 days, with 0 deaths. By flood insurance claims since 1978 (OpenFEMA, as of September 8, 2026), Bon Homme County ranks 2756th of 2,942 U.S. counties.

The National Flood Insurance Program has paid $24,000 on 2 claims filed in Bon Homme County; the most in one year was 2 in 2019. Claims count insured losses only: uninsured flood damage is not in this file.

Source: FEMA OpenFEMA NFIP Redacted Claims, as of September 8, 2026; claims by year of loss, payments in the dollars of the year paid. OpenFEMA dataset page.

FEMA's modeled risk for Bon Homme County

FEMA's National Risk Index rates Bon Homme County Very Low overall, with an expected annual loss of $7.2 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 Bon Homme County

1. Charles Mix County 958
2. Yankton County 878
3. Hutchinson County 832
4. Bon Homme County 812
5. Knox County, NE 776

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