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Tornado in Lyman County, South Dakota
40 tornadoes events in the NCEI Storm Events record, 1950 to 2026. Event types counted: Tornado.
NCEI notes that Storm Data is compiled from a variety of sources including the National Weather Service, other federal, state and local agencies, the media and the public; that property and crop damage figures are estimates; and that some events are recorded by NWS forecast zone rather than by county. FEMA notes that NFIP claim records are redacted and aggregated to protect the privacy of policyholders. Storm records through 30 Jun 2026.
NCEI records 40 tornado events in Lyman County, South Dakota, between 1950 and 2026, spread over 17 years.
July is the busiest month, with 22 of the recorded events. The last 20 years account for 5 events against 20 in the 20 years before, a change that reflects reporting practice as much as weather.
The county holds 2.1% of the 1,947 tornado events recorded in South Dakota; its 2.4 per 100 square miles compares with 2.6 statewide.
By rating: 27 at (E)F0, 7 at (E)F1, 3 at (E)F2, 2 at (E)F3, 0 at (E)F4, 0 at (E)F5 and 1 unrated. Tornadoes before 2007 carry the original Fujita rating.
Compared with South Dakota
| Measure | Lyman County | South Dakota | US |
|---|---|---|---|
| Tornado events since 1950 | 40 | 1,947 | 81,281 |
| Per 100 square miles | 2.4 | 2.6 | 2.3 |
| Per 10,000 residents | 106.3 | 21.7 | 2.4 |
| Deaths recorded | 0 | 19 | 6,410 |
| Busiest month | July | June | May |
By year
Seasonality
0Feb
0Mar
0Apr
0May
4Jun
8Jul
22Aug
6Sep
0Oct
0Nov
0Dec
0
Magnitude distribution
Enhanced Fujita scale wind estimates
- EF0/F0
- 65–85 mph (EF0)
- EF1/F1
- 86–110 mph (EF1)
- EF2/F2
- 111–135 mph (EF2)
- EF3/F3
- 136–165 mph (EF3)
- EF4/F4
- 166–200 mph (EF4)
- EF5/F5
- over 200 mph (EF5)
- Unrated
- no rating recorded
Tornado rating as recorded (Fujita scale before February 2007, Enhanced Fujita after).
Recorded events
All 40 events, most recent first. Magnitude is hail size, tornado rating or wind speed as recorded.
| Date | Event type | Magnitude | Property damage | Crop damage | Deaths | Injuries | Geography |
|---|---|---|---|---|---|---|---|
| 15 Jul 2025 | Tornado | EF0 | — | — | — | — | County |
| 12 Jun 2022 | Tornado | EF unrated | — | — | — | — | County |
| 9 Aug 2019 | Tornado | EF0 | — | — | — | — | County |
| 8 May 2011 | Tornado | EF0 | — | — | — | — | County |
| 23 Jul 2010 | Tornado | EF0 | — | — | — | — | County |
| 11 Jun 2003 | Tornado | F0 | — | — | — | — | County |
| 11 Jun 2003 | Tornado | F0 | — | — | — | — | County |
| 11 Jun 2003 | Tornado | F0 | — | — | — | — | County |
| 24 Jul 2002 | Tornado | F0 | — | — | — | — | County |
| 9 May 1999 | Tornado | F0 | — | — | — | — | County |
| 5 Aug 1987 | Tornado | F0 | — | — | — | — | County |
| 5 Aug 1987 | Tornado | F0 | — | — | — | — | County |
| 5 Aug 1987 | Tornado | F0 | — | — | — | — | County |
| 5 Aug 1987 | Tornado | F2 | $250K | — | — | — | County |
| 5 Aug 1987 | Tornado | F1 | — | — | — | — | County |
| 9 Jul 1987 | Tornado | F1 | $3K | — | — | — | County |
| 6 Jul 1987 | Tornado | F1 | — | — | — | — | County |
| 6 Jul 1987 | Tornado | F0 | — | — | — | — | County |
| 6 Jul 1987 | Tornado | F0 | — | — | — | — | County |
| 6 Jul 1987 | Tornado | F0 | — | — | — | — | County |
| 6 Jul 1987 | Tornado | F0 | — | — | — | — | County |
| 6 Jul 1987 | Tornado | F1 | $3K | — | — | — | County |
| 6 Jul 1987 | Tornado | F0 | — | — | — | — | County |
| 6 Jul 1987 | Tornado | F0 | — | — | — | — | County |
| 6 Jul 1987 | Tornado | F0 | — | — | — | — | County |
| 8 May 1986 | Tornado | F0 | — | — | — | — | County |
| 28 May 1985 | Tornado | F0 | — | — | — | — | County |
| 20 Jul 1982 | Tornado | F0 | $30 | — | — | — | County |
| 20 Jul 1982 | Tornado | F0 | $30 | — | — | — | County |
| 20 Jul 1982 | Tornado | F0 | $30 | — | — | — | County |
| 20 Jul 1982 | Tornado | F0 | $30 | — | — | — | County |
| 30 Jul 1972 | Tornado | F0 | — | — | — | — | County |
| 9 Jul 1971 | Tornado | F3 | — | — | — | — | County |
| 9 Jul 1971 | Tornado | F3 | — | — | — | 2 | County |
| 6 Jun 1971 | Tornado | F0 | — | — | — | — | County |
| 4 Jun 1971 | Tornado | F2 | — | — | — | — | County |
| 10 Jul 1969 | Tornado | F1 | — | — | — | — | County |
| 21 Jun 1962 | Tornado | F1 | — | — | — | — | County |
| 25 Jul 1960 | Tornado | F2 | $25K | — | — | — | County |
| 26 Jun 1960 | Tornado | F1 | $3K | — | — | — | County |
Questions and answers
How many tornado events has Lyman County had?
40 events in the NCEI Storm Events record between 1950 and 2026. Reporting of tornadoes became far more complete after 1996, so early decades undercount.
When was the last recorded tornado event in Lyman County?
15 Jul 2025 (Tornado, EF0). Records reach NCEI about 120 days after the month ends.
What was the most damaging tornado event recorded in Lyman County?
The tornado of 5 Aug 1987, with property damage estimated by NCEI at $250K.
How does Lyman County compare with South Dakota for tornado?
2.4 events per 100 square miles against 2.6 statewide; the county holds 40 of the state's 1,947 recorded events.
Provenance
NOAA NCEI Storm Events Database, yearly details files through 30 Jun 2026, public domain. County-recorded events plus zone-recorded events whose forecast zone is named for the county (marked "Forecast zone"). Population and area from the US Census Bureau (2021). Built 1 Oct 2026. See the methodology, the Tornado hub and the county page.