Right now
The most recent data we hold from HEAT GOV arrived 25 minutes ago, and this point is in it.
Nothing else has been detected within 20 km in the last 24 hours.
This alert is in force until 17 September 2026, 07:30 UTC.
It is the 28th strongest of the 39 detections recorded within 20 km of this point since 15 March 2026. The last comparable one was on 11 July 2026.
What the source measured
HEAT GOV reported: * WHAT...Heat index values up to 105. * WHERE...In Illinois, Fayette IL, Montgomery IL, Calhoun IL, Greene IL, Jersey IL, and Macoupin IL Counties. In Missouri, Boone MO, Callaway MO, Lincoln MO, and Montgomery MO Counties. * WHEN...Until 8 PM CDT Friday. * IMPACTS...Hot temperatures and high ...
Urban PEI: 560,335 within a heuristic 50 km radius; not unique people.
Nearby, since 15 March 2026
- May 21, 2026 · score 48 · 2.6 km
- May 22, 2026 · score 43 · 7.1 km
- July 11, 2026 · score 48 · 7.7 km
How we know
One source: HEAT GOV. Not yet confirmed by a second, independent source.
Our own score for this event is 41 out of 100.
This is our versioned heuristic index, not source severity or a calibrated probability. Urban PEI does not count unique people.
Computed under scoring rules v5. Rows carrying other versions were judged by different rules and are not directly comparable.
Event Data
| Type | Severe Weather |
| Severity | Medium |
| Calamity Score (ours) | 41 / 100 |
| Legacy data-support index | 0.70/1 |
| Coordinates | 39.0431, -90.6700 |
| Nearest City | O'Fallon (26 km) |
| Urban exposure index (PEI) | 560.3K within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-09-16T16:29:00.000Z |
| Source | http://www.weather.gov |
Physical priority index · v5. Heuristic priority, not calibrated probability, predictive accuracy or damage. The legacy data-support index combines assigned source support and field availability. Urban PEI is distance-weighted and does not count unique people; zero does not establish that nobody is present. Model cards.
Source and revision timeline
Source: heat_gov. Occurrence: 2026-09-16T16:29:00.000Z.
First archived: 2026-09-16T17:01:55.486Z. Material modification: not recorded.
Retained revisions are prospective; earlier versions may be unavailable. No revision entry does not prove that a record never changed.
Score Breakdown
Technical Details
| Event | Heat Advisory |
| Urgency | Expected |
| Certainty | Likely |
| Onset | 2026-09-16T11:29:00-05:00 |
| Expires | 2026-09-17T02:30:00-05:00 |
| AreaDesc | Greene; Macoupin; Montgomery; Fayette; Calhoun; Jersey; Boone; Callaway; Montgomery; Lincoln |
| SenderName | NWS St Louis MO |
| ZonesUsedForCentroid | 10 |
| ZoneCount | 10 |
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.
Review the area, threshold and delivery channel in your account.
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