Right now
The most recent data we hold from HEAT GOV arrived 33 minutes ago, and this point is not in it. We record detections, not passes: an absence is not proof that nothing is there.
Nothing else has been detected within 20 km in the last 24 hours.
This alert expired on 4 September 2026 at 23:00 UTC. It is kept here as a record.
It is the 12th strongest of the 134 detections recorded within 20 km of this point since 15 March 2026. The last comparable one was on 2 September 2026.
What the source measured
HEAT GOV reported: * WHAT...Heat index values up to 105 expected. * WHERE...Portions of northwest and west central Iowa, northeast Nebraska, and south central and southeast South Dakota. * WHEN...From 1 PM this afternoon to 6 PM CDT this evening. * IMPACTS...Hot temperatures and high humidity may cause heat illn...
An estimated 82,821 people live within 50 km of this point.
Nearby, since 15 March 2026
- June 1, 2026 · score 46 · 3.5 km
How we know
One source: HEAT GOV. Not yet confirmed by a second, independent source.
Our own score for this event is 32 out of 100, at 68 % 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 | 68% |
| Coordinates | 42.8707, -96.7413 |
| Nearest City | Sioux City (50 km) |
| Population Exposed | 82.8K within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-09-04T18:00:00.000Z |
| Source | http://www.weather.gov |
Score Breakdown
Technical Details
| Event | Heat Advisory |
| Urgency | Expected |
| Certainty | Likely |
| Onset | 2026-09-04T13:00:00-05:00 |
| Expires | 2026-09-04T18:00:00-05:00 |
| AreaDesc | Sioux; O'Brien; Plymouth; Cherokee; Buena Vista; Woodbury; Ida; Dixon; Dakota; Charles Mix; Douglas; Hutchinson; Turner; Lincoln; Bon Homme; Yankton; Clay; Union |
| SenderName | NWS Sioux Falls SD |
| ZonesUsedForCentroid | 9 |
| ZoneCount | 18 |
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 32/100 (United States), based on data from heat_gov. Source: Calamity.live, a platform aggregating real-time data from 185 scientific monitoring sources.