NHC HURDAT2 · SPC Tornado Database
Hurricanes and Tornadoes That Hit Groton, SD
Every tropical system within 75 miles since 1851 and every tornado within 25 miles since 1950.
Data: NOAA NHC HURDAT2 and NOAA SPC tornado and hail reports, through 2025 · Updated
No tropical storm or hurricane has passed within 75 miles of Groton, South Dakota since records began in 1851. Since 1950, 91 tornadoes have touched down within 25 miles, 6 of them rated EF3 or stronger.
- Hurricanes
- 0
- Tropical storms
- 0
- Tornadoes
- 91
- EF3 or stronger
- 6
within 75 mi, since 1851
below hurricane strength
within 25 mi, since 1950
3 deaths in all
What the records show for Groton
The strongest of the 91 tornadoes within 25 miles was an F4 on June 23, 2002; its path came within 21 miles. The deadliest, an F3 on July 1, 1973, killed 1 person. Of the 91, 7 had paths within 5 miles of the city centre, and 24 have come since 2000. June has had the most tornadoes, 41. The most recent tornado was on July 13, 2025. Groton has more tornadoes within 25 miles than 63% of the 61 South Dakota cities on this site. Hail has been reported within 10 miles 84 times since 1961, with stones up to 4 inches (softball size). Of the 61 South Dakota cities, 69% have more hail reports within 10 miles than Groton.
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Tornadoes within 25 miles of Groton
By decade
- 2020s6
- 2010s6
- 2000s12(2 EF3+)
- 1990s18(1 EF3+)
- 1980s16
- 1970s14(1 EF3+)
- 1960s11(2 EF3+)
- 1950s8
| Date | Rating | Distance | Path | Killed / injured |
|---|---|---|---|---|
| Jun 23, 2002 | F4 | 21 mi | 9 mi | 0 / 0 |
| Jul 1, 1973 | F3 | 23 mi | 0.3 mi | 1 / 3 |
| Jun 21, 1961 | F3 | 3 mi | 156.3 mi | 1 / 7 |
| Jun 23, 2002 | F3 | 23 mi | 10 mi | 0 / 0 |
| May 31, 1996 | F3 | 10 mi | 32 mi | 0 / 1 |
| Jun 25, 1969 | F3 | 3 mi | 1.5 mi | 0 / 6 |
| Jul 31, 1966 | F2 | 15 mi | 2.3 mi | 1 / 3 |
| Jul 17, 1996 | F2 | 14 mi | 5 mi | 0 / 0 |
| Jun 15, 1978 | F2 | 8 mi | 0.1 mi | 0 / 15 |
| Jun 28, 1961 | F2 | 24 mi | 49.7 mi | 0 / 0 |
| Jun 28, 1955 | F2 | 10 mi | 5.4 mi | 0 / 0 |
| Apr 19, 1955 | F2 | 18 mi | 4.6 mi | 0 / 0 |
The strongest 12 of 91, by rating and then by deaths. Ratings before February 2007 are on the original Fujita scale.
Hail in Groton
The Storm Prediction Center has 84 hail reports within 10 miles of Groton since 1961, made on 52 separate days. Of these, 65 were 1 inch across or larger, and 7 reached 2 inches. The largest, 4 inches (softball size), fell on June 21, 1961. The most recent report is from July 31, 2024. June has the most reports, 29.
Source: NOAA Storm Prediction Center severe weather reports, data through 2025.
Weather by month in Groton
The nearest NOAA station with 1991–2020 climate normals is Aberdeen, SD, 14 miles west of Groton at 1,302 feet. July is the warmest, with an average high of 85°F and low of 60°F; January is the coolest, at 24°F and 2°F. Highs reach 90°F on about 15 days a year, almost all from June to September. Lows fall below freezing on about 179 nights a year. Snowfall averages 42.7 inches a year, most of it in February. That 21.8 inches is more than at 18 of the 43 South Dakota stations used on this site (42%). Webster, 30 miles east, has its own station (Webster, SD): 26.2 inches a year, 4.4 more than here, and a July average high of 81°F against 85°F.
| Month | High °F | Low °F | Precip. in | Days ≥ 0.1" | Snow in |
|---|---|---|---|---|---|
| Jan | 24 | 2 | 0.6 | 2 | 7.8 |
| Feb | 29 | 6 | 0.6 | 2 | 8.6 |
| Mar | 42 | 19 | 0.9 | 2 | 6.3 |
| Apr | 58 | 31 | 1.9 | 4 | 4.2 |
| May | 70 | 44 | 3.3 | 6 | 0.0 |
| Jun | 80 | 55 | 3.8 | 7 | 0.0 |
| Jul | 85 | 60 | 3.1 | 6 | 0.0 |
| Aug | 83 | 57 | 2.2 | 4 | 0.0 |
| Sep | 75 | 47 | 2.0 | 4 | 0.0 |
| Oct | 59 | 33 | 2.1 | 4 | 1.3 |
| Nov | 43 | 19 | 0.7 | 2 | 6.5 |
| Dec | 29 | 8 | 0.6 | 2 | 8.0 |
| Year | 56 | 32 | 21.8 | 46 | 42.7 |
Averages for 1991–2020 at Aberdeen, SD (1,302 ft), from NOAA NCEI U.S. Climate Normals. Normals describe the station; the farther a place is from it, and the bigger the difference in height, the more its weather can differ.
Floods, thunderstorm wind and lightning near Groton
Since 1996, the National Weather Service has logged 76 flood, rain, thunderstorm wind and lightning events that began within 10 miles of Groton: 51 thunderstorm wind reports, 24 floods and 1 flash flood. None is recorded as killing or injuring anyone; the NWS estimated $10,000 in property and crop damage. The strongest thunderstorm gust on record here was 110 mph, on July 31, 2008.
Source: NOAA NCEI Storm Events Database, events whose starting point is on record, 1996 to June 30, 2026. Damage is the NWS estimate in the dollars of the year, not insured losses, and NWS notes that some reports are unverified.
Flood insurance claims, disaster declarations and FEMA risk ratings
Flood insurance policyholders in Groton's ZIP code 57445 have filed 14 claims with the National Flood Insurance Program since 1993, and were paid $247,000 for buildings and contents, in the dollars of each year. 29% of the claims carry the name of a storm or flood event; the rest have no event name. Of the 28 South Dakota cities on this site with 10 or more claims, 5 have fewer than Groton.
Brown County, which includes Groton, has been named in 19 federal disaster or emergency declarations since 1969, 16 of them major disasters (by incident: 9 floods, 6 severe storms, 2 biological emergencies, 1 coastal storm). The latest major disaster declaration was Flooding, on July 6, 2023. FEMA's National Risk Index gives Brown County a Relatively Low rating for natural hazard risk overall; by hazard: Relatively Moderate for tornadoes, hail and strong wind; Relatively Low for inland flooding and heat waves; Very Low for lightning. It models the county's expected loss from all 18 hazards it covers at $36.6 million a year, the 4th highest of 66 South Dakota counties; of the hazards above, the largest share, $11.3 million (31%), is from inland flooding.
Claims: FEMA, OpenFEMA Dataset FIMA NFIP Redacted Claims – v3, summed over ZIP codes; payments in the dollars of each year, not adjusted for inflation. Declarations: Disaster Declarations Summaries – v2, by county. Retrieved October 25, 2026. 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).
Risk ratings: FEMA, National Risk Index county table, December 2025 (v1.20), retrieved October 26, 2026; ratings compare counties nationwide, are meant for planning and are no substitute for a local risk assessment. This product uses the Federal Emergency Management Agency's National Risk Index dataset API or downloadable datasets 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).
What counts as a pass, the distances and the sources: how this storm history is built.
Cities near Groton
- Aberdeen, SD18 mi
- Webster, SD30 mi
- Ipswich, SD43 mi
- Oakes, ND44 mi
- Redfield, SD46 mi
- Sisseton, SD55 mi
- Watertown, SD62 mi
- Lisbon, ND71 mi
- Huron, SD75 mi
- Milbank, SD76 mi
- Ortonville, MN85 mi
- Wahpeton, ND90 mi
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