McCook County, South Dakota

What hazards hit McCook County most?

The most frequent records are hail reports: 194 since 1959. 46% of its hail reports since 1959 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 McCook County had?

NOAA records 42 tornadoes in McCook County from 1953 to 2026, the strongest rated F4, with 6 deaths and 151 injuries recorded in the county. That is 3rd 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 44 tornadoes whose track touched McCook County since 1950 (NOAA's county records number 42: they file a crossing tornado once per county segment, and the two databases differ on some tracks); along their whole tracks they killed 6 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 McCook County?

The most recent record with damage, injuries or deaths is the June 20, 2024 flood ($1.6 million in damage in 2025 dollars).

Rainfall amounts across McCook County from June 20-22 ranged from 5 to 8 inches. Widespread overland flooding ensued with additional flooding along the East Fork Vermillion River, West Fork Vermillion River, and Wolf Creek. Flood waters damaged 10 to 15 homes in Montrose, 8 to 10 homes in Salem, and 3 to 4 homes in Spencer. Numerous others reported water in their basements. Sewage backup also occurred in Montrose, Salem, and Spencer. Residential flood damages are estimated to be nearly 547 thousand dollars. At the peak of flooding, U.S. Highway 81 was closed in more than four locations and South Dakota Highway 38 was closed at Montrose. Many other roads and culverts across the county were damaged or washed out. Preliminary damage assessments estimate loss to public infrastructure across the county to be nearly 1.17 million dollars. …
National Weather Service event narrative, NOAA Storm Events Database (search the full record, event 1193330)

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 McCook 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: 33 records against 10 in the decade before, 33 of them forecast-zone records. High wind and dust storms in the 2020-26: 29 records against 6 in the decade before, 29 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 McCook 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?

46% of its hail reports since 1959 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 McCook County

FEMA's register lists 21 declarations that include McCook County: 18 major disasters, 3 emergencies and 0 fire management assistance declarations. Most were for severe storm (9) and flood (7).

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 McCook County had?

NOAA's Storm Events Database holds 30 flood or flash flood records for McCook County from 1997 to 2024, on 24 days, with 0 deaths. By flood insurance claims since 1978 (OpenFEMA, as of September 8, 2026), McCook County ranks 1928th of 2,942 U.S. counties.

The National Flood Insurance Program has paid $576,000 on 29 claims filed in McCook County; the most in one year was 11 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 McCook County

FEMA's National Risk Index rates McCook County Relatively Low overall, with an expected annual loss of $21.4 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 McCook County

1. Minnehaha County 1,554
2. Hutchinson County 832
3. Turner County 787
4. McCook County 745
5. Lake County 664
6. Hanson County 566
7. Miner County 537

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 McCook CountyThe hazard risk calculator: 18 hazards beside the county's record
• Download McCook County's FEMA declarations (CSV)21 rows: every declaration that named the county, for your own analysis