This alert expired on 2 September 2026 at 02:17 UTC. It is kept here as a record.
No stronger detection stands among the 93 recorded within 20 km of this point since 15 March 2026 — 4 others scored the same. Another comparable one was recorded here earlier the same day.
What the source measured
NOAA reported: Tornado Warning issued September 1 at 9:08PM CDT until September 1 at 9:15PM CDT by NWS Sioux Falls SD
Nearby, since 15 March 2026
- June 30, 2026 · score 28 · 12.4 km
How we know
One source: NOAA. Not yet confirmed by a second, independent source.
Our own score for this event is 46 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 | critical |
| Calamity Score (ours) | 46 / 100 |
| Our confidence | 61% |
| Coordinates | 42.8467, -97.1467 |
| Nearest City | Sioux City (72 km) |
| Impact Tier | minor |
| Timestamp | 2026-09-02T02:08:00.000Z |
| Source | https://api.weather.gov/alerts/urn%3Aoid%3A2.49.0.1.840.0.9ef1b4042cd1269f3b710357b6d002bb1e2dbb4e.001.1 |
Score Breakdown
Technical Details
| Event | Tornado Warning |
| Urgency | Immediate |
| Certainty | Observed |
| AreaDesc | Clay, SD; Yankton, SD |
| Headline | Tornado Warning issued September 1 at 9:08PM CDT until September 1 at 9:15PM CDT by NWS Sioux Falls SD |
| Expires | 2026-09-01T21:17:00-05:00 |
| SenderName | NWS Sioux Falls SD |
| HasExactCoords | true |
Safety Information
If a tornado warning is issued: go to a basement or an interior room on the lowest floor, away from windows. A vehicle and a mobile home are not shelter. Cover your head and neck. Wait for the official all-clear before going outside, and watch for downed power lines and gas leaks afterwards.
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 46/100 (United States), based on data from noaa. Source: Calamity.live, a platform aggregating real-time data from 185 scientific monitoring sources.