This alert is in force until 2 September 2026, 04:00 UTC.
It is the 208th strongest of the 238 detections recorded within 20 km of this point since 10 March 2026. The last comparable one was on 13 August 2026.
What the source measured
NOAA reported: Severe Thunderstorm Watch issued September 1 at 3:52PM CDT until September 1 at 11:00PM CDT by NWS Sioux Falls SD
An estimated 181,553 people live within 50 km of this point.
Nearby, since 10 March 2026
- August 13, 2026 · score 43 · 0.0 km
- August 12, 2026 · score 43 · 0.0 km
- August 11, 2026 · score 43 · 0.0 km
How we know
One source: NOAA. Not yet confirmed by a second, independent source.
Our own score for this event is 37 out of 100, at 80 % 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) | 37 / 100 |
| Our confidence | 80% |
| Coordinates | 42.0000, -93.2000 |
| Nearest City | Marshalltown (25 km) |
| Population Exposed | 181.6K within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-09-01T20:52:00.000Z |
| Source | https://api.weather.gov/alerts/urn%3Aoid%3A2.49.0.1.840.0.049eabddf2531127ad1b6dcf660a00f2932efc34.001.1 |
Score Breakdown
Technical Details
| Event | Severe Thunderstorm Watch |
| Urgency | Future |
| Certainty | Possible |
| AreaDesc | Lyon, IA; Plymouth, IA; Sioux, IA; Pipestone, MN; Rock, MN; Dixon, NE; Aurora, SD; Bon Homme, SD; Charles Mix, SD; Clay, SD; Davison, SD; Douglas, SD; Gregory, SD; Hanson, SD; Hutchinson, SD; Lake, SD; Lincoln, SD; McCook, SD; Miner, SD; Minnehaha, SD; Moody, SD; Sanborn, SD; Turner, SD; Union, SD; Yankton, SD |
| Headline | Severe Thunderstorm Watch issued September 1 at 3:52PM CDT until September 1 at 11:00PM CDT by NWS Sioux Falls SD |
| Expires | 2026-09-01T23:00:00-05:00 |
| SenderName | NWS Sioux Falls SD |
| HasExactCoords | false |
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 near Marshalltown?
Calamity.live data shows a weather event with CalamityScore 37/100, near Marshalltown (United States), based on data from noaa. Source: Calamity.live, a platform aggregating real-time data from 185 scientific monitoring sources.