This alert expired on 2 September 2026 at 03:45 UTC. It is kept here as a record.
It is the 51st strongest of the 81 detections recorded within 20 km of this point since 16 March 2026. Another comparable one was recorded here earlier the same day.
What the source measured
NOAA reported: Severe Thunderstorm Warning issued September 1 at 10:18PM CDT until September 1 at 10:45PM CDT by NWS Sioux Falls SD
Nearby, since 16 March 2026
- June 30, 2026 · score 28 · 18.4 km
How we know
Confirmed by 3 independent sources, including NOAA.
Our own score for this event is 23 out of 100, at 71 % confidence.
The score is ours, computed from intensity, exposed population and local history — not the source’s.
Event Data
| Type | Severe weather |
| Severity | high |
| Calamity Score (ours) | 23 / 100 |
| Our confidence | 71% |
| Coordinates | 43.0383, -97.4050 |
| Nearest City | Sioux Falls (78 km) |
| Impact Tier | minor |
| Timestamp | 2026-09-02T03:18:00.000Z |
| Source | https://api.weather.gov/alerts/urn%3Aoid%3A2.49.0.1.840.0.58d7e82af9967520c2943517a574c714dd9c97b9.001.1 |
Score Breakdown
Technical Details
| Event | Severe Thunderstorm Warning |
| Urgency | Immediate |
| Certainty | Observed |
| AreaDesc | Bon Homme, SD; Charles Mix, SD; Lyon, IA; O'Brien, IA; Osceola, IA; Sioux, IA; Nobles, MN; Rock, MN; Lincoln, SD; Knox, NE |
| Headline | Severe Thunderstorm Warning issued September 1 at 10:18PM CDT until September 1 at 10:45PM CDT by NWS Sioux Falls SD |
| Expires | 2026-09-01T22:45:00-05:00 |
| SenderName | NWS Sioux Falls SD |
| HasExactCoords | true |
| MergedCount | 3 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.58d7e82af9967520c2943517a574c714dd9c97b9.001.1","noaa_urn:oid:2.49.0.1.840.0.08313553d925ee48054df786bb735b8124ba8026.002.1","noaa_urn:oid:2.49.0.1.840.0.45dd3df255a06f53882a36bf5a764008843ecd05.001.1"] |
| Spc ReportType | hail |
| Spc Speed | 200 |
| Spc Location | Randolph |
| Spc County | Cedar |
| Spc State | NE |
| Spc Comments | Report from Randolph Fire Department with picture of 2 inch hail. Report relayed via NWSChat and time estimated via radar. (OAX) |
| Iem TypeSummary | D |
| Iem City | Vermillion |
| Iem County | Clay |
| Iem State | SD |
Safety Information
Always follow official guidance from your local emergency management agency. This platform provides scientific monitoring data and is not a substitute for official warnings. If you are in immediate danger, contact your local emergency number.
Series begins 10 February 2026. Comparisons refer to that period only. Collection gap: 14-26 August 2026.
This data is aggregated algorithmically from scientific sources. Not a replacement for official emergency warnings.
Want to know when something happens in this area?
Calamity.live data shows a weather event with CalamityScore 23/100 (United States), based on data from noaa. Source: Calamity.live, a platform aggregating real-time data from 185 scientific monitoring sources.