This alert expired on 4 September 2026 at 22:15 UTC. It is kept here as a record.
It is the 18th strongest of the 33 detections recorded within 20 km of this point since 4 April 2026. Another comparable one was recorded here earlier the same day.
What the source measured
NOAA reported: Severe Thunderstorm Warning issued September 4 at 4:55PM CDT until September 4 at 5:15PM CDT by NWS La Crosse WI
Nearby, since 4 April 2026
- September 4, 2026 · score 28 · 5.1 km
- July 5, 2026 · score 22 · 12.3 km
- September 4, 2026 · score 28 · 14.2 km
How we know
Confirmed by 3 independent sources, including NOAA.
Our own score for this event is 16 out of 100, at 71 % 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) | 16 / 100 |
| Our confidence | 71% |
| Coordinates | 43.0357, -91.4491 |
| Nearest City | La Crosse (87 km) |
| Impact Tier | minor |
| Timestamp | 2026-09-04T21:55:00.000Z |
| Source | https://api.weather.gov/alerts/urn%3Aoid%3A2.49.0.1.840.0.f5505791bbe79f11cf30ddb9f72211d1dc2b09f3.001.1 |
Score Breakdown
Technical Details
| Event | Severe Thunderstorm Warning |
| Urgency | Immediate |
| Certainty | Observed |
| AreaDesc | Clayton, IA; Grant, WI; Fayette, IA; Winneshiek, IA |
| Headline | Severe Thunderstorm Warning issued September 4 at 4:55PM CDT until September 4 at 5:15PM CDT by NWS La Crosse WI |
| Expires | 2026-09-04T17:15:00-05:00 |
| SenderName | NWS La Crosse WI |
| HasExactCoords | true |
| MergedCount | 2 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.f5505791bbe79f11cf30ddb9f72211d1dc2b09f3.001.1","noaa_urn:oid:2.49.0.1.840.0.6d7cbf0bbc738a57602de0e706715b1edcbd6398.001.1"] |
| Spc ReportType | wind |
| Spc Speed | UNK |
| Spc Location | 4 NNE Waukon |
| Spc County | Allamakee |
| Spc State | IA |
| Spc Comments | Report of several trees down across Allamakee County. Time and location estimated from radar. (ARX) |
| Iem TypeSummary | D |
| Iem City | 4 NNE Waukon |
| Iem County | Allamakee |
| Iem State | IA |
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 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 16/100 (United States), based on data from noaa. Source: Calamity.live, a platform aggregating real-time data from 185 scientific monitoring sources.