Pennington County, South Dakota

What hazards hit Pennington County most?

The most frequent records are hail reports: 1,626 since 1955. 68% of its hail reports since 1955 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 Pennington County had?

NOAA records 49 tornadoes in Pennington County from 1953 to 2019, the strongest rated EF2, with 0 deaths and 10 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 51 tornadoes whose track touched Pennington County since 1950 (NOAA's county records number 49: 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 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 Pennington County?

The most recent record with damage, injuries or deaths is the July 1, 2022 flash flood ($1.0 million in damage in 2025 dollars).

Over three inches of rain fell in an hour over Ellsworth Air Force Base and parts of Box Elder. Runoff from the heavy rain flooded streets, homes, and businesses. Several streets were flooded on Ellsworth Air Force Base and throughout northern and eastern portions of Box Elder. At least 50 mobile homes were surrounded by water and ten to 15 homes were flooded with water up to six feet deep, mostly along the east side of North Ellsworth Road. Several businesses reported that their parking lots were flooded.
National Weather Service event narrative, NOAA Storm Events Database (search the full record, event 1036312)

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 Pennington 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?

68% of its hail reports since 1955 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 Pennington County

FEMA's register lists 21 declarations that include Pennington County: 13 major disasters, 3 emergencies and 5 fire management assistance declarations. Most were for flood (6) and fire (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 Pennington County had?

NOAA's Storm Events Database holds 79 flood or flash flood records for Pennington County from 1996 to 2023, on 58 days, with 0 deaths. By flood insurance claims since 1978 (OpenFEMA, as of September 8, 2026), Pennington County ranks 1153rd of 2,942 U.S. counties.

The National Flood Insurance Program has paid $556,000 on 135 claims filed in Pennington County; the most in one year was 18 in 1997. 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 Pennington County

FEMA's National Risk Index rates Pennington County Relatively Low overall, with an expected annual loss of $40.8 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 Pennington County

1. Pennington County 3,309
2. Meade County 2,685
3. Custer County 1,466
4. Lawrence County 1,268
5. Jackson County 959
6. Weston County, WY 911
7. Haakon County 843

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