Grant County

Every recorded tornado

1. Injuries and deaths are for the tornado’s whole path, which may extend beyond the county. Deaths recorded within Grant County: 0.
2. Weak tornadoes were under-recorded before Doppler radar coverage became national in the early 1990s, so earlier decades read low. Ratings use the Fujita scale before February 2007 and the Enhanced Fujita scale after.

Storm Prediction Center severe weather database, 1950 to 2025.

Smoke overhead

1. A smoke day is a date on which a smoke plume traced by NOAA Hazard Mapping System analysts from satellite imagery covered this place's point (the county's population centre or the city centre). Counts here are of medium or heavy smoke. Since 2018 analysts have often drawn light smoke as one area over most of the continent, so light-smoke counts are not comparable from year to year. The plumes show smoke anywhere in the air above, not air quality at the ground, and smoke hidden by cloud is missed.

NOAA Hazard Mapping System smoke analysis, 2011 to 2026, retrieved October 30, 2026.

Claims by ZIP code

This product uses the Federal Emergency Management Agency's OpenFEMA API, but is not endorsed by FEMA. The Federal Government or FEMA cannot vouch for the data or analyses derived from these data after the data have been retrieved from the Agency's website(s).

OpenFEMA NFIP Redacted Claims v3, refreshed August 4, 2026. NOAA Storm Events through 2026.

River crests

River gauges

1. Crests are the highest and the recent crests the National Weather Service lists for each river gauge in the county that has a flood stage, not every flood. Flood categories use each gauge's current flood stages; crests from before levees, dams or channel changes may not be comparable. Crests measured on an old datum are left out of the rankings.

NOAA National Water Prediction Service gauge records, retrieved October 30, 2026.

1. The Palmer Drought Severity Index is computed by NOAA each month from the county's average temperature and precipitation, relative to the county's own climate. Zero is normal; -3 or lower is severe drought and -4 or lower extreme drought. It describes the long-term balance of moisture, not water supply or crop losses.

NOAA NCEI nClimDiv county Palmer Drought Severity Index, 1895 to September 2026, issued October 6, 2026.

Every earthquake of magnitude 4 or more within 50 miles

1. Earthquakes of magnitude 2.5 or more in the USGS Comprehensive Catalog since 1900. Within 50 miles means the epicentre lies within 50 miles of the county boundary (or inside the county).
2. Small earthquakes were under-recorded before the modern seismic networks of the 1970s and are still missed in remote areas, so early decades read low. Magnitudes are as the catalogue reports them and mix scales (moment, local and body-wave).

USGS ANSS Comprehensive Earthquake Catalog, 1900 to present, retrieved October 30, 2026.

More event types since 1996

Costliest events since 1996

1. Dec 25, 2016Ice Storm, Grant$1.8 million
   National Weather Service narrative

   An intense surface low pressure area moved from northeast Colorado to South Dakota from the 24th through the 26th. This storm was unusually warm for the region for late December and produced record breaking heavy rain along with flooding in some cases. Significant icing occurred across areas at or just below the freezing point, which resulted in widespread tree and power pole and line damage to the area. Some downed branches and trees fell onto homes across the region. This storm also brought high winds along with snow and blizzard conditions to the region. This significant storm resulted in massive power outages, stranded motorists and closed roads. ||Ice accumulations were…

2. Jun 11, 2008Flash Flood$250,000
   National Weather Service narrative

   A strong inflow of moist and unstable air into and over a surface warm front resulted in training thunderstorms and very heavy rain across parts of northeast South Dakota. Rainfall amounts of 2 to 6 inches occurred across much of the area resulting in widespread flash flooding. Many roads, bridges, and cropland were damaged by the flooding. In Milbank, many basements were flooded and/or received sewer backup.

3. Apr 7, 2001Flood, Grant$240,000
   National Weather Service narrative

   Heavy rain of 1 to 3 inches combined with snowmelt runoff brought flooding to parts of northeast South Dakota. Many roads across Clark, Grant, Hamlin, Deuel, and Roberts counties were flooded and damaged. Floodwater moving towards the town of Willow Lake overpowered culverts and flooded several homes and several streets. Highway 28 had to be cut through to allow the water to flow away from the town, averting a disaster. Highwater from the creek west of Corona in far Southern Roberts county flowed towards Corona. As a result, 3 1/2 feet of water coursed through town flooding several homes and streets and knocking out the sewer system. Also, 1000 feet of railroad track was damaged…

4. Apr 10, 2023Flood$150,000
   National Weather Service narrative

   The snowfall during the season in northeast and central South Dakota exceeded normal levels, with many locations ranking among the top 10 for the snowiest seasons. Additionally, the late spring conditions were unusually cold, resulting in a persistent and exceptionally deep snowpack until early April. The depth of the snowpack ranged from 15 to 30 plus inches, containing approximately 4 to 8 inches of snow water equivalent. However, the weather pattern shifted to abnormally warm conditions in the middle of April. Starting from April 9th, temperatures rapidly rose into the 40s and 50s in areas with deep snowpack, and occasionally reached the 60s and 70s thereafter. The rapid…

5. Jun 21, 2013Thunderstorm Wind$131,000
   National Weather Service narrative

   Eighty mph winds caused major tree and structural damage in and around Milbank. Many trees were downed.

6. Apr 1, 2019Flood$76,000
   National Weather Service narrative

   The continuation of snowmelt from a much above normal snowfall winter combined with a historic heavy snow/blizzard in mid-April resulted in widespread flooding across central and northeast South Dakota. Countless roads along with thousands of acres of cropland were flooded throughout April. Impacts include damaged roads, culverts, and bridges, and livestock, homes, and businesses were affected. Delayed planting resulted across all of the region as well. Cattle and calves were stressed by the cold and wet pattern, as the mud and cold caused some sickness with the livestock. Flooded roads made it difficult for many farmers or ranchers to get to their fields or livestock. There was a…

7. Jul 14, 2013Flash Flood$40,000
   National Weather Service narrative

   A line of storms moving across north central South Dakota during the early morning hours on the 14th became heavy rainfall producing thunderstorms for northeastern South Dakota. Rainfall amounts of 2 to 5 inches caused mainly localized flooding. However in Grant County, a 20 foot wide by 17 foot deep culvert on 468th Avenue in Twin Brooks was washed away by flash flooding. The Grant County Highway Department said fixing the culvert would cost more than $40,000 dollars.

8. Mar 22, 2009Flash Flood$20,000
   National Weather Service narrative

   Flash flooding damaged a bridge along with several township roads in Grant county.

9. Aug 18, 2017Lightning$10,000
   National Weather Service narrative

   Lightning blew out a transformer which snapped a power pole and downed some power lines in Milbank.

10. Aug 10, 2007Lightning$2,000
    National Weather Service narrative

    Lightning struck a home in Milbank damaging some of the siding, sheet rock, electrical wiring and outlets, and blew a chunk of cement out of the basement.

1. Storm Events records before 1996 cover only tornadoes, thunderstorm wind and hail. Damage figures are as reported by the National Weather Service at the time, not adjusted for inflation.

NOAA NCEI Storm Events Database, 1950 to 2026, issued October 26, 2026.

All-time high

110°FJul 21, 1934

All-time low

−40°FJan 13, 1916

Warmest night

78°F4 times, most recently Jul 16, 2012

Coldest day

−25°FFeb 8, 1899

Wettest day

7.14 inMay 27, 1931

Snowiest day

19.0 inApr 25, 2008

Hottest year

1987mean 48.7°F

Coldest year

1917mean 38.5°F

Wettest year

197740.04 in

Driest year

197610.82 in

Snowiest season

81.7 in2018-19

Station Watertown Regional Airport (USW00014946), 1,741 ft elevation, 31.8 miles from the population centre. Daily records from 1893 to October 26, 2026; 99.8% of days in the last 30 years are complete. Records at a single station can differ from a city’s official threaded record, which may combine several stations.

NOAA NCEI Global Historical Climatology Network Daily.

This product uses the Federal Emergency Management Agency's OpenFEMA API, but is not endorsed by FEMA. The Federal Government or FEMA cannot vouch for the data or analyses derived from these data after the data have been retrieved from the Agency's website(s).

OpenFEMA Disaster Declarations Summaries, retrieved October 30, 2026. Statewide declarations are not listed.

Neighbouring counties

• Tornadoes NOAA Storm Prediction Center severe weather database, through 2025.
• Tropical cyclones NOAA National Hurricane Center HURDAT2 (Atlantic; Northeast and Central Pacific), through 2025.
• Wildfire USGS/USFS Monitoring Trends in Burn Severity, through 2026.
• Storm events NOAA NCEI Storm Events Database, through 2026.
• Flood insurance OpenFEMA NFIP Redacted Claims v3, refreshed August 4, 2026.
• Declarations OpenFEMA Disaster Declarations Summaries v2, retrieved October 30, 2026.
• Weather records NOAA NCEI Global Historical Climatology Network Daily, station USW00014946.
• River crests NOAA National Weather Service, National Water Prediction Service river gauges, retrieved October 30, 2026.
• Drought NOAA NCEI nClimDiv county Palmer Drought Severity Index, through September 2026.
• Smoke NOAA NESDIS Hazard Mapping System smoke analysis, retrieved October 30, 2026.
• Earthquakes USGS ANSS Comprehensive Earthquake Catalog (ComCat), retrieved October 30, 2026.

Joins, thresholds and known limits are set out in the methodology. Found an error? Report it. Page built October 30, 2026.