Corson County, South Dakota

What hazards hit Corson County most?

The most frequent records are hail reports: 311 since 1962. 66% of its hail reports since 1962 fell in June and July. 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 Corson County had?

NOAA records 23 tornadoes in Corson County from 1953 to 2025, the strongest rated F2, with 0 deaths and 4 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 23 tornadoes whose track touched Corson County since 1950 (NOAA's county records number 23, 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 Corson County?

The most recent record with damage, injuries or deaths is the March 19, 2020 winter weather (1 death).

A woman died in a one-vehicle crash four miles south of McLaughlin in Corson county in part due to icy roads. She was southbound on South Dakota Highway 63 when she lost control of her vehicle on ice with the vehicle going into the ditch and rolling. She was not wearing a seat belt and was thrown from the vehicle and died.
National Weather Service event narrative, NOAA Storm Events Database (search the full record, event 882846)

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 Corson 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?

66% of its hail reports since 1962 fell in June and July. The two busiest months are in violet.

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

Federal disaster declarations for Corson County

FEMA's register lists 16 declarations that include Corson County: 13 major disasters, 3 emergencies and 0 fire management assistance declarations. Most were for severe storm (8) and biological (2).

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 Corson County had?

NOAA's Storm Events Database holds 55 flood or flash flood records for Corson County from 1997 to 2025, on 50 days, with 0 deaths. By flood insurance claims since 1978 (OpenFEMA, as of September 8, 2026), Corson County ranks 2830th of 2,942 U.S. counties.

The National Flood Insurance Program has paid $450 on 1 claim filed in Corson County; the most in one year was 1 in 1978. 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 Corson County

FEMA's National Risk Index rates Corson County Very Low overall, with an expected annual loss of $7.1 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 Corson County

1. Perkins County 1,026
2. Corson County 939
3. Dewey County 814
4. Ziebach County 738
5. Walworth County 663
6. Campbell County 519
7. Adams County, ND 510
8. Emmons County, ND 503
9. Sioux County, ND 418

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 Corson CountyThe hazard risk calculator: 18 hazards beside the county's record
• Download Corson County's FEMA declarations (CSV)16 rows: every declaration that named the county, for your own analysis