Right now
The most recent data we hold from NOAA arrived 12 minutes ago, and this point is not in it. We record detections, not passes: an absence is not proof that nothing is there.
2 other detections within 20 km in the last 24 hours, the nearest <1 km from here.
This alert expired on 7 September 2026 at 11:01 UTC. It is kept here as a record.
It is the 7th strongest of the 28 detections recorded within 20 km of this point since 13 April 2026. Another comparable one was recorded here earlier the same day.
What the source measured
NOAA reported: Flash Flood Warning issued September 7 at 5:51AM CDT until September 7 at 6:00AM CDT by NWS Sioux Falls SD
An estimated 82,821 people live within 50 km of this point.
Nearby, since 13 April 2026
- July 8, 2026 · score 39 · 15.2 km
- July 2, 2026 · score 46 · 23.9 km
How we know
One source: NOAA. Not yet confirmed by a second, independent source.
Our own score for this event is 32 out of 100, at 81 % confidence.
The score is ours, computed from intensity, exposed population and local history — not the source’s.
Computed under scoring rules v4. Rows carrying other versions were judged by different rules and are not directly comparable.
Event Data
| Type | Severe Weather |
| Severity | Medium |
| Calamity Score (ours) | 32 / 100 |
| Our confidence | 81% |
| Coordinates | 42.5500, -95.9322 |
| Nearest City | Sioux City (39 km) |
| Population Exposed | 82.8K within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-09-07T10:51:00.000Z |
| Source | https://api.weather.gov/alerts/urn%3Aoid%3A2.49.0.1.840.0.9c7e413f27f7dc6651c3718f0a2b8dcc11723077.001.1 |
Score Breakdown
Technical Details
| Event | Flash Flood Warning |
| Urgency | Immediate |
| Certainty | Likely |
| AreaDesc | Plymouth, IA; Woodbury, IA |
| Headline | Flash Flood Warning issued September 7 at 5:51AM CDT until September 7 at 6:00AM CDT by NWS Sioux Falls SD |
| Expires | 2026-09-07T06:01:00-05:00 |
| SenderName | NWS Sioux Falls SD |
| HasExactCoords | true |
Safety Information
During flooding: never walk, swim, or drive through floodwaters. Six inches of moving water can knock you down, and one foot of water can sweep away a vehicle. Move to higher ground if waters rise. After flooding, avoid contact with floodwater which may contain sewage, chemicals, or debris. Follow local emergency service guidance.
Series begins 8 March 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 32/100 (United States), based on data from noaa. Source: Calamity.live, a platform aggregating real-time data from 185 scientific monitoring sources.