This alert expired on 1 September 2026 at 23:30 UTC. It is kept here as a record.
No stronger detection stands among the 30 recorded within 20 km of this point since 27 April 2026 — 17 others scored the same. Another comparable one was recorded here earlier the same day.
What the source measured
NOAA reported: Severe Thunderstorm Warning issued September 1 at 5:50PM CDT until September 1 at 6:30PM CDT by NWS Sioux Falls SD
Nearby, since 27 April 2026
- September 2, 2026 · score 28 · 7.8 km
- September 1, 2026 · score 28 · 12.6 km
How we know
Confirmed by 3 independent sources, including NOAA.
Our own score for this event is 28 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) | 28 / 100 |
| Our confidence | 71% |
| Coordinates | 42.6433, -99.0848 |
| Nearest City | Mitchell (146 km) |
| Impact Tier | minor |
| Timestamp | 2026-09-01T22:50:00.000Z |
| Source | https://api.weather.gov/alerts/urn%3Aoid%3A2.49.0.1.840.0.7ccafe49e84c3a9ea193f967c3d00fb66efcfeb5.001.1 |
Score Breakdown
Technical Details
| Event | Severe Thunderstorm Warning |
| Urgency | Immediate |
| Certainty | Observed |
| AreaDesc | Charles Mix, SD; Gregory, SD; Boyd, NE; Rock, NE and 4 more areas |
| Headline | Severe Thunderstorm Warning issued September 1 at 5:50PM CDT until September 1 at 6:30PM CDT by NWS Sioux Falls SD |
| Expires | 2026-09-01T18:30:00-05:00 |
| SenderName | NWS Sioux Falls SD |
| HasExactCoords | true |
| MergedCount | 9 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.7ccafe49e84c3a9ea193f967c3d00fb66efcfeb5.001.1","noaa_urn:oid:2.49.0.1.840.0.bf857c084f90044815dbc4c25f8bf0c6b10429c6.001.1","noaa_urn:oid:2.49.0.1.840.0.27b73e32e38ab99ed38106d640ec8d2a3ddb918e.001.1","noaa_urn:oid:2.49.0.1.840.0.8c61943a4687b57e2fbc1075efd3d0e244f51940.001.1","noaa_urn:oid:2.49.0.1.840.0.3598ced96dd14a804ece33ac837d5007c7fa144c.001.1","noaa_urn:oid:2.49.0.1.840.0.1aa6a2034f3fb7f43a2b175a7027159f84d2a24f.001.1","noaa_urn:oid:2.49.0.1.840.0.3354133e802e04718e4db7b5fc1e11b98f7f4d74.001.1","noaa_urn:oid:2.49.0.1.840.0.171268566de3d27aa5b39a4de740800165f3893f.001.1","noaa_urn:oid:2.49.0.1.840.0.8393676c60d6fdf86c2442d7c3a60cab33a110b1.002.1"] |
| Spc ReportType | hail |
| Spc Speed | 275 |
| Spc Location | Pickstown |
| Spc County | Charles Mix |
| Spc State | SD |
| Spc Comments | (FSD) |
| Iem TypeSummary | H |
| Iem Magnitude | 1 |
| Iem Unit | Inch |
| Iem City | 3 ESE Naper |
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 28/100 (United States), based on data from noaa. Source: Calamity.live, a platform aggregating real-time data from 185 scientific monitoring sources.