Lyman County, South Dakota severe weather history spans 605 recorded events between 1957 and 2025. The dominant hazard is thunderstorm wind, accounting for 48.1% of all recorded events. It ranks #572 nationally and #15 in South Dakota.
605
Recorded events
2
Direct deaths
8
Direct injuries
$363K
Property damage
The record
What the Lyman County, South Dakota severe weather history record shows
Across the archive, Lyman County, South Dakota severe weather history averages 8.9 recorded events a year. The busiest stretch on record is the 2010s, with 236 events logged in that decade alone. Roughly 80 events fall before 1990 and 525 from 1990 onward — a gap that reflects the expansion of NOAA reporting practice as much as the weather itself.
The deadliest hazard in the Lyman County, South Dakota record is flash flood, responsible for 2 direct deaths. The costliest is tornado, with $283K in reported property damage. In total, 7 distinct hazard types appear in this county archive, each listed with its own dated record below.
By hazard type
Every hazard type recorded in Lyman County
| Hazard | Events | Deaths | Damage | Max | Span |
|---|---|---|---|---|---|
| Thunderstorm Wind | 291 | 0 | $50K | 90 | 1957–2025 |
| Hail | 234 | 0 | $0 | 8 | 1957–2025 |
| Tornado | 40 | 0 | $283K | F3 | 1960–2025 |
| Flood | 21 | 0 | $31K | 0 | 2009–2024 |
| Flash Flood | 12 | 2 | $0 | 0 | 1999–2025 |
| Funnel Cloud | 6 | 0 | $0 | 0 | 2007–2025 |
| Wildfire | 1 | 0 | $0 | 0 | 2000–2000 |
Decade by decade
Lyman County, South Dakota severe weather history by decade
Reporting practice changed over time — early decades are undercounted, not calmer.
Tornado tracks
Paths crossing this county
44 mapped tornado paths intersect this county: 43 touched down inside it and 1 crossed in from a neighbouring county. This comes from path geometry, not county-tagged reports.
| Date | Scale | Deaths | Injuries | Path length | Origin |
|---|---|---|---|---|---|
| 1971-07-09 | EF3 | 0 | 0 | 0.1 mi | Touched down here |
| 1971-07-09 | EF3 | 0 | 2 | 0.1 mi | Touched down here |
| 1987-08-05 | EF2 | 0 | 0 | 1.2 mi | Touched down here |
| 1971-06-04 | EF2 | 0 | 0 | 0.1 mi | Touched down here |
| 1960-07-25 | EF2 | 0 | 0 | 10.4 mi | Touched down here |
| 1993-06-27 | EF1 | 0 | 0 | 0.5 mi | Touched down here |
| 1987-07-09 | EF1 | 0 | 0 | 0.5 mi | Touched down here |
| 1987-07-06 | EF1 | 0 | 0 | 0.1 mi | Touched down here |
| 1987-07-06 | EF1 | 0 | 0 | 1.0 mi | Touched down here |
| 1987-08-05 | EF1 | 0 | 0 | 0.1 mi | Touched down here |
Significant events
Deadliest events on record in Lyman County
| Date | Type | Location | Deaths | Injuries | Damage |
|---|---|---|---|---|---|
| Jun 21, 2011 | Flash Flood | LOWER BRULE | 2 | 0 | $0 |
| Jul 23, 2010 | Hail | VIVIAN | 0 | 5 | $0 |
| Jul 10, 1971 | Tornado | 0 | 2 | $0 | |
| Jun 5, 1994 | Thunderstorm Wind | Presho/Vivien | 0 | 1 | $50K |
From the record
What the reports say
Written by National Weather Service staff at the time of the event · public domain
Very heavy rainfall of 5 to 7 inches brought flash flooding to mainly eastern Lyman county. Many roads were flooded with some washed out. Two women died in two separate vehicles after driving into a washed out portion of a road. One woman was found 100 yards downstream while the other woman was found 4 miles downstream. The accidents were believed to happen between 930 and 10 am. The location was 9 miles north of Reliance on BIA 10 just north of the intersection with Highway 47.
The White River rose above the flood stage of 15 feet near Oacoma in the late afternoon hours of February 11th. The White River crested at 17.64 feet around noon on February 13th before it fell below flood stage in the mid morning hours of the 15th.
A peak wind gust of 80 mph was observed by the South Dakota State University mesonet station near Lower Brule. West Central Electric Cooperative reported multiple power outages due to broken poles and wires in and around Lower Brule.
Context
Risk, population and federal disasters
Very Low
FEMA NRI risk rating
3,724
Population (ACS)
$166K
Median home value
30
Federal declarations
| Declared | Incident | Title | Type |
|---|---|---|---|
| Apr 5, 2020 | Biological | COVID-19 PANDEMIC | DR |
| Apr 5, 2020 | Biological | COVID-19 PANDEMIC | DR |
| Apr 5, 2020 | Biological | COVID-19 PANDEMIC | DR |
| Apr 5, 2020 | Biological | COVID-19 PANDEMIC | DR |
| Apr 5, 2020 | Biological | COVID-19 PANDEMIC | DR |
| Apr 5, 2020 | Biological | COVID-19 PANDEMIC | DR |
Quick answers
Frequently asked
How many severe weather events have been recorded in Lyman County, South Dakota?
605 events are on record between 1957 and 2025, causing 2 direct deaths and $363K in property damage.
What is the most common severe weather hazard in Lyman County?
Thunderstorm Wind, with 291 recorded events — 48.1% of everything in the archive for this county.
How many tornadoes have crossed Lyman County?
44 mapped tornado paths intersect the county boundary; 43 of them touched down inside it. This is derived from path geometry, not county-tagged reports.
How many federal disaster declarations cover Lyman County?
30 federal disaster declarations from FEMA include Lyman County, each tied to a specific incident period.
How risky is Lyman County compared with the rest of the country?
FEMA's National Risk Index rates Lyman County as very low risk, placing it in the 26 percentile of its state for expected annual loss.
Where does the Lyman County, South Dakota severe weather history data come from?
Every figure is drawn from United States federal public-domain records: NOAA/NCEI Storm Events for the event archive, NOAA SPC SVRGIS for mapped tornado paths, FEMA for disaster declarations and risk ratings, and the U.S. Census for population context. Dates are shown in UTC and recent entries may still be revised by NOAA.
Nearby
Neighbouring counties
- Lincoln County 591
- McCook County 391
- Lawrence County 703
- McPherson County 386
- Lake County 334
- Marshall County 346
Cite this page
“Lyman County, South Dakota.” Severe Weather History. severeweatherhistory.com/county/south-dakota/lyman-county/ · Data: NOAA/NCEI, FEMA, U.S. Census — public domain.