Slope County, North Dakota
County storm and disaster record · FIPS 38087 · population 699 · 1,215 sq mi
NOAA's Storm Events Database holds 391 records for Slope County, North Dakota from 1950 through June 30, 2026, on 323 days; the most frequent are hail reports (96 records). 220 of them are forecast-zone records, which the National Weather Service files once per zone: a county covered by several zones receives each one, so a single storm can add several records on the same day. The most damaging was the April 4, 1997 blizzard ($2.6 million in 2025 dollars). FEMA has issued 10 declarations naming the county since 1978, 8 of them for natural hazards; the latest for a natural hazard was “Severe Winter Storm” on October 31, 2013.
The record, 1950 to 2026
Storm records filed for the county each year (2026 to June 30, 2026). Before 1996 NOAA recorded only tornadoes (from 1950), thunderstorm wind and hail (from 1955).
- recorded, no damage figure
- under $100,000
- $100,000 or more
- $1 million or more
- $10 million or more, or a death
- $100 million or more, or 10 deaths
- a year's colour: its recorded damage or deaths
- a year with a death
- 1955: wind and hail recorded from 1955
- 1996: all 48 event types from 1996
- Storm records
- 391on 323 days, 1950 to June 30, 2026
- Deaths recorded
- 00 injuries
- Damage, 2025 dollars
- $11Mas filed (scale steps before 1993)
- Tornadoes
- 11strongest F1
- FEMA declarations
- 10latest 2020
Source: NOAA NCEI Storm Events Database, records through June 30, 2026 (file revision 20260918); damage converted to 2025 dollars with the BLS CPI-U. Search the record at NCEI. BLS consumer price index.
What hazards hit Slope County most?
The most frequent records are hail reports: 96 since 1981. 76% of its hail reports since 1981 fell in June and July. The rank column places the county among North Dakota's counties by days with a record per 1,000 square miles of land over each hazard's complete period.
| Hazard | Records | Days | First, last | Killed | Injured | Damage | Rank in state |
|---|---|---|---|---|---|---|---|
| Hail | 96 | 68 | 1981-2025 | 0 | 0 | $955K | 45 of 53 |
| Winter storms | 87 | 86 | 1996-2026 | 0 | 0 | $7.2M | 38 of 53 |
| High wind and dust storms | 85 | 85 | 1996-2026 | 0 | 0 | $26K | 5 of 53 |
| Severe thunderstorm wind | 53 | 35 | 1978-2026 | 0 | 0 | $1.2M | 52 of 53 |
| Drought | 22 | 22 | 2021-2025 | 0 | 0 | – | 8 of 53 |
| Extreme cold | 21 | 20 | 1996-2025 | 0 | 0 | – | 46 of 53 |
| Tornadoes | 11 | 9 | 1960-2010 | 0 | 0 | $386K | 51 of 53 |
| Fog, smoke and funnel clouds | 8 | 6 | 2009-2023 | 0 | 0 | – | 38 of 53 |
| Wildfires | 3 | 3 | 2006-2012 | 0 | 0 | $129K | 3 of 53 |
| Heavy rain | 2 | 2 | 2009-2011 | 0 | 0 | – | 21 of 53 |
| Floods | 1 | 1 | 2007-2007 | 0 | 0 | $142K | 53 of 53 |
| Heat | 1 | 1 | 2011-2011 | 0 | 0 | $918K | 36 of 53 |
| Lightning | 1 | 1 | 2011-2011 | 0 | 0 | $7K | 33 of 53 |
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 Slope County had?
NOAA records 11 tornadoes in Slope County from 1960 to 2010, the strongest rated F1, with 0 deaths and 0 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 11 tornadoes whose track touched Slope County since 1950 (NOAA's county records number 11, the same count); along their whole tracks they killed 0 people.
Map of the strongest tornado tracks in North Dakota.
Every tornado record filed for Slope County (11)
| Date | Place | Character | Killed | Injured | Damage |
|---|---|---|---|---|---|
| 2010-09-09 | Marmarth, Slope County | EF0 0.82 mi x 40 yd | 0 | 0 | $41K |
| 2010-07-26 | Amidon, Slope County | EF0 5.34 mi x 30 yd | 0 | 0 | – |
| 2001-07-03 | Amidon, Slope County | F0 7 mi x 40 yd | 0 | 0 | – |
| 1999-06-20 | Amidon, Slope County | F0 2 mi x 25 yd | 0 | 0 | $9K |
| 1991-06-08 | Slope County | F0 0.1 mi x 10 yd | 0 | 0 | $25K step |
| 1991-06-08 | Slope County | F1 0.1 mi x 7 yd | 0 | 0 | $3K step |
| 1983-07-17 | Slope County | F0 0.3 mi x 10 yd | 0 | 0 | $30 step |
| 1983-07-17 | Slope County | F0 0.3 mi x 10 yd | 0 | 0 | $30 step |
| 1972-05-19 | Slope County | F1 15.5 mi x 50 yd | 0 | 0 | $3K step |
| 1965-05-23 | Slope County | 0 | 0 | $25K step | |
| 1960-08-06 | Slope County | 0 | 0 | $3K step |
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, 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 Slope County?
The most recent record with damage, injuries or deaths is the July 20, 2017 thunderstorm wind ($90,000 in damage in 2025 dollars).
Four grain grain bins were damaged by the thunderstorm winds.
National Weather Service event narrative, NOAA Storm Events Database (search the full record, event 715234)
| Date | Record | Character | Killed | Injured | Damage |
|---|---|---|---|---|---|
| 2026-06-27 | Thunderstorm WindAmidon, Slope County | 56 kt wind | 0 | 0 | – |
| 2026-06-27 | Thunderstorm WindAmidon, Slope County | 59 kt wind | 0 | 0 | – |
| 2026-06-07 | Thunderstorm WindAmidon, Slope County | 51 kt wind | 0 | 0 | – |
| 2026-06-07 | Thunderstorm WindAmidon, Slope County | 52 kt wind | 0 | 0 | – |
| 2026-05-14 | High WindSlope County · forecast zone Slope | 52 kt wind | 0 | 0 | – |
| 2026-04-03 | Heavy SnowSlope County · forecast zone Slope | 0 | 0 | – | |
| 2026-03-14 | Heavy SnowSlope County · forecast zone Slope | 0 | 0 | – | |
| 2026-03-12 | High WindSlope County · forecast zone Slope | 70 kt wind | 0 | 0 | – |
| 2026-01-15 | High WindSlope County · forecast zone Slope | 63 kt wind | 0 | 0 | – |
| 2025-12-18 | BlizzardSlope County · forecast zone Slope | 0 | 0 | – | |
| 2025-12-17 | High WindSlope County · forecast zone Slope | 79 kt wind | 0 | 0 | – |
| 2025-12-09 | High WindSlope County · forecast zone Slope | 51 kt wind | 0 | 0 | – |
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
| Date | Record | Character | Killed | Injured | Damage |
|---|---|---|---|---|---|
| 1997-04-04 | BlizzardSlope County · forecast zone Slope | 0 | 0 | $2.6M | |
| 2011-07-16 | Excessive HeatSlope County · forecast zone Slope | 0 | 0 | $918K | |
| 2010-01-24 | BlizzardSlope County · forecast zone Slope | 0 | 0 | $796K | |
| 2016-07-10 | HailAmidon, Slope County | 2.75 in hail | 0 | 0 | $492K |
| 2017-07-20 | Thunderstorm WindAmidon, Slope County | 80 kt wind | 0 | 0 | $482K |
| 2006-04-19 | BlizzardSlope County · forecast zone Slope | 0 | 0 | $366K | |
| 1996-08-03 | Thunderstorm WindNew England, Slope County | 0 | 0 | $339K | |
| 2017-07-20 | Thunderstorm WindAmidon, Slope County | 70 kt wind | 0 | 0 | $108K |
Before 1993 NOAA filed damage by category, not amount, so the list above starts in 1993. The highest category filed here before then (entered as $25K, in the dollars of the day) holds: May 23, 1965 (tornado, Slope County); June 8, 1991 (tornado, Slope County).
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 Slope 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).
| Hazard | 1950s | 1960s | 1970s | 1980s | 1990s | 2000s | 2010s | 2020-26 |
|---|---|---|---|---|---|---|---|---|
| Hail | 0 | 0 | 0 | 5 | 18 | 24 | 39 | 10 |
| Winter storms | – | – | – | – | 15 | 28 | 28 | 16 |
| High wind and dust storms | – | – | – | – | 3 | 21 | 28 | 33 |
| Severe thunderstorm wind | 0 | 0 | 1 | 3 | 3 | 5 | 14 | 27 |
| Drought | – | – | – | – | 0 | 0 | 0 | 22 |
| Extreme cold | – | – | – | – | 2 | 7 | 8 | 4 |
Source: NOAA NCEI Storm Events Database, records per calendar decade; zone records from the CZ_TYPE field (Z).
What time of year?
76% of its hail reports since 1981 fell in June and July. The two busiest months are in violet.
The values, month by month
Jan 37 · Feb 25 · Mar 28 · Apr 25 · May 24 · Jun 60 · Jul 81 · Aug 31 · Sep 12 · Oct 21 · Nov 20 · Dec 27 (records).
Source: NOAA NCEI Storm Events Database, records by the month they began.
Federal disaster declarations for Slope County
FEMA's register lists 10 declarations that include Slope County: 7 major disasters, 3 emergencies and 0 fire management assistance declarations. Most were for severe storm (3) and biological (2).
| Declared | Number | Type | Title |
|---|---|---|---|
| 2020-04-01 | DR-4509 | Biological | Covid-19 Pandemic |
| 2020-03-13 | EM-3477 | Biological | Covid-19 |
| 2013-10-31 | DR-4154 | Severe Storm | Severe Winter Storm |
| 2010-02-26 | DR-1879 | Severe Storm | Severe Winter Storm |
| 2005-11-21 | DR-1616 | Snowstorm | Severe Winter Storm and Record and/Or Near Record Snow |
| 2005-09-13 | EM-3247 | Coastal Storm | Hurricane Katrina Evacuation |
| 1997-04-07 | DR-1174 | Flood | Severe Flooding,Severe Winter Storms, Snowmelt, Spring Rains |
| 1997-01-12 | DR-1157 | Severe Storm | Severe Winter Storms and Blizzard Conditions |
| 1978-04-17 | DR-554 | Flood | Storms, Ice Jams, Snowmelt & Flooding |
| 1978-02-16 | EM-3061 | Snowstorm | Blizzard & Snowstorms |
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.
FEMA's modeled risk for Slope County
FEMA's National Risk Index rates Slope County Very Low overall, with an expected annual loss of $1.1 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.
| Hazard | Risk rating | Expected annual loss | Modeled frequency |
|---|---|---|---|
| Cold Wave | Relatively Low | $597K | 11 a year (modeled) |
| Wildfire | Very Low | $28K | once in about 1,423 years (modeled) |
| Drought | Very Low | $12K | 29 modeled event-days a year |
| Hail | Very Low | $96K | 2.4 a year (modeled) |
| Winter Weather | Very Low | $23K | 17 a year (modeled) |
| Ice Storm | Very Low | $11K | once in about 2 years (modeled) |
| Heat Wave | Very Low | $40K | 1 modeled event-days a year |
| Landslide | Very Low | $21 | once in about 3 years (modeled) |
Source: FEMA National Risk Index, county table, December 2025 release. FEMA's National Risk Index map.
Counties that share a border with Slope County
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 North DakotaEvery North Dakota tornado since 1950 and the counties with the most per square mile
- Hail in North DakotaThe state's hail reports, by county, year and month
- The North Dakota recordEvery hazard in the state, its deadliest events and its federal declarations
- FEMA's risk rating for each hazard in Slope CountyThe hazard risk calculator: 18 hazards beside the county's record
- Download Slope County's FEMA declarations (CSV)10 rows: every declaration that named the county, for your own analysis