This alert expired on 1 September 2026 at 23:30 UTC. It is kept here as a record.
No stronger detection stands among the 29 recorded within 20 km of this point since 27 April 2026 — 18 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 6:08PM CDT until September 1 at 6:30PM CDT by NWS Sioux Falls SD
Nearby, since 27 April 2026
- September 1, 2026 · score 28 · 1.4 km
- September 2, 2026 · score 28 · 18.2 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 | 42.5434, -99.0749 |
| Nearest City | Norfolk (148 km) |
| Impact Tier | minor |
| Timestamp | 2026-09-01T23:08:00.000Z |
| Source | https://api.weather.gov/alerts/urn%3Aoid%3A2.49.0.1.840.0.e9015af7d22206ccc1801066b1b0b4d9c03af44e.001.1 |
Score Breakdown
Technical Details
| Event | Severe Thunderstorm Warning |
| Urgency | Immediate |
| Certainty | Observed |
| AreaDesc | Charles Mix, SD; Douglas, SD; Hutchinson, SD; Boyd, NE; Holt, NE; Keya Paha, NE; Rock, NE; Holt, NE; Rock, NE and 3 more areas |
| Headline | Severe Thunderstorm Warning issued September 1 at 6:08PM 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 | 6 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.e9015af7d22206ccc1801066b1b0b4d9c03af44e.001.1","noaa_urn:oid:2.49.0.1.840.0.e86ea0d2b5f799998d04f1c8ce14b8538db00e18.001.1","noaa_urn:oid:2.49.0.1.840.0.30dc98caeae53e21d6431822461df31da8203188.001.1","noaa_urn:oid:2.49.0.1.840.0.52c18625411650806ba28b83d30d89d8f8f882d9.001.1","noaa_urn:oid:2.49.0.1.840.0.052f35154c914e1ea1a96749d7f06d6d4032e549.001.1","noaa_urn:oid:2.49.0.1.840.0.7ccafe49e84c3a9ea193f967c3d00fb66efcfeb5.001.1"] |
| Spc ReportType | hail |
| Spc Speed | 100 |
| Spc Location | 2 NNE Anoka |
| Spc County | Boyd |
| Spc State | NE |
| Spc Comments | Mostly peas to nickels but largest was quarters. Time estimated from radar. (LBF) |
| Iem TypeSummary | H |
| Iem Magnitude | 1 |
| Iem Unit | Inch |
| Iem City | 11 SSE Bassett |
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.