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Tornado in Slope County, North Dakota
11 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.
Slope County, North Dakota, has 11 tornado events in the NCEI record since 1950, with at least one in 8 different years.
July is the busiest month, with 4 of the recorded events. The last 20 years account for 2 events against 4 in the 20 years before, a change that reflects reporting practice as much as weather.
The county holds 0.6% of the 1,799 tornado events recorded in North Dakota; its 0.9 per 100 square miles compares with 2.6 statewide.
By rating: 7 at (E)F0, 2 at (E)F1, 0 at (E)F2, 0 at (E)F3, 0 at (E)F4, 0 at (E)F5 and 2 unrated. Tornadoes before 2007 carry the original Fujita rating.
Compared with North Dakota
| Measure | Slope County | North Dakota | US |
|---|---|---|---|
| Tornado events since 1950 | 11 | 1,799 | 81,281 |
| Per 100 square miles | 0.9 | 2.6 | 2.3 |
| Per 10,000 residents | 159.4 | 23.2 | 2.4 |
| Deaths recorded | 0 | 29 | 6,410 |
| Busiest month | July | June | May |
By year
Seasonality
0Feb
0Mar
0Apr
0May
2Jun
3Jul
4Aug
1Sep
1Oct
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 11 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 |
|---|---|---|---|---|---|---|---|
| 9 Sep 2010 | Tornado | EF0 | $30K | — | — | — | County |
| 26 Jul 2010 | Tornado | EF0 | — | — | — | — | County |
| 3 Jul 2001 | Tornado | F0 | — | — | — | — | County |
| 20 Jun 1999 | Tornado | F0 | $5K | — | — | — | County |
| 8 Jun 1991 | Tornado | F1 | $3K | — | — | — | County |
| 8 Jun 1991 | Tornado | F0 | $25K | — | — | — | County |
| 17 Jul 1983 | Tornado | F0 | $30 | — | — | — | County |
| 17 Jul 1983 | Tornado | F0 | $30 | — | — | — | County |
| 19 May 1972 | Tornado | F1 | $3K | — | — | — | County |
| 23 May 1965 | Tornado | — | $25K | — | — | — | County |
| 6 Aug 1960 | Tornado | — | $3K | — | — | — | County |
Questions and answers
How many tornado events has Slope County had?
11 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 Slope County?
9 Sep 2010 (Tornado, EF0). Records reach NCEI about 120 days after the month ends.
What was the most damaging tornado event recorded in Slope County?
The tornado of 9 Sep 2010, with property damage estimated by NCEI at $30K.
How does Slope County compare with North Dakota for tornado?
0.9 events per 100 square miles against 2.6 statewide; the county holds 11 of the state's 1,799 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.