This alert expired on 1 September 2026 at 21:45 UTC. It is kept here as a record.
It is the 18th strongest of the 30 detections recorded within 20 km of this point since 15 March 2026. The last comparable one was on 7 August 2026.
What the source measured
NOAA reported: Severe Thunderstorm Warning issued September 1 at 4:06PM CDT until September 1 at 4:45PM CDT by NWS Sioux Falls SD
Nearby, since 15 March 2026
- September 1, 2026 · score 16 · 13.2 km
How we know
One source: NOAA. Not yet confirmed by a second, independent source.
Our own score for this event is 16 out of 100, at 61 % confidence.
The score is ours, computed from intensity, exposed population and local history — not the source’s.
Event Data
| Type | Severe weather |
| Severity | medium |
| Calamity Score (ours) | 16 / 100 |
| Our confidence | 61% |
| Coordinates | 43.1100, -99.1599 |
| Nearest City | Mitchell (113 km) |
| Impact Tier | minor |
| Timestamp | 2026-09-01T21:06:00.000Z |
| Source | https://api.weather.gov/alerts/urn%3Aoid%3A2.49.0.1.840.0.fa3ee4d0ef5ad27523b41f467dfc6cf621f6b5dd.001.1 |
Score Breakdown
Technical Details
| Event | Severe Thunderstorm Warning |
| Urgency | Immediate |
| Certainty | Observed |
| AreaDesc | Brule, SD; Charles Mix, SD; Gregory, SD; Boyd, NE; Holt, NE; Boyd, NE; Keya Paha, NE |
| Headline | Severe Thunderstorm Warning issued September 1 at 4:06PM CDT until September 1 at 4:45PM CDT by NWS Sioux Falls SD |
| Expires | 2026-09-01T16:45:00-05:00 |
| SenderName | NWS Sioux Falls SD |
| HasExactCoords | true |
| MergedCount | 3 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.fa3ee4d0ef5ad27523b41f467dfc6cf621f6b5dd.001.1","noaa_urn:oid:2.49.0.1.840.0.7807216033c046eec9e50d200c691aba659fdb6b.001.1","noaa_urn:oid:2.49.0.1.840.0.6c2947c3c08e6863adb3ebd881adf5ea38a3f63a.001.1"] |
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 16/100 (United States), based on data from noaa. Source: Calamity.live, a platform aggregating real-time data from 185 scientific monitoring sources.