This alert expired on 21 May 2026 at 18:00 UTC. It is kept here as a record.
It is the 4th strongest of the 38 detections recorded within 20 km of this point since 15 March 2026. The last comparable one was on 18 May 2026. 11 more were recorded here in the fortnight before it.
What the source measured
NOAA reported: Flood Warning issued May 20 at 10:33PM EDT until May 23 at 3:12AM EDT by NWS Indianapolis IN
An estimated 522,409 people live within 50 km of this point.
Nearby, since 15 March 2026
- May 22, 2026 · score 43 · 5.4 km
- July 11, 2026 · score 48 · 8.7 km
- March 15, 2026 · score 48 · 14.4 km
How we know
One source: NOAA. Not yet confirmed by a second, independent source.
Our own score for this event is 48 out of 100, at 82 % confidence.
The score is ours, computed from intensity, exposed population and local history — not the source’s.
Computed under scoring rules v1. Rows carrying other versions were judged by different rules and are not directly comparable.
Event Data
| Type | Severe Weather |
| Severity | Medium |
| Calamity Score (ours) | 48 / 100 |
| Our confidence | 82% |
| Coordinates | 39.0649, -90.6812 |
| Nearest City | O'Fallon (28 km) |
| Population Exposed | 522.4K within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-05-21T15:00:00.000Z |
| Source | https://api.weather.gov/alerts/merged_Flood Warning_noaa_urn:oid:2.49.0.1.840.0.258988fe1ac413e4df2f30b4dab2ab59 |
Score Breakdown
Technical Details
| Event | Flood Warning |
| Urgency | Immediate |
| Certainty | Observed |
| AreaDesc | Bartholomew, IN; Johnson, IN; Shelby, IN; Lawrence, IL; Bartholomew, IN and 32 more areas |
| Headline | Flood Warning issued May 20 at 10:33PM EDT until May 23 at 3:12AM EDT by NWS Indianapolis IN |
| Expires | 2026-05-21T14:00:00-04:00 |
| SenderName | NWS Indianapolis IN |
| HasExactCoords | true |
| MergedCount | 38 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.258988fe1ac413e4df2f30b4dab2ab597a67710b.001.1","noaa_urn:oid:2.49.0.1.840.0.a007a4b93819df5d693d53d935d7e012c01c59b7.001.1","noaa_urn:oid:2.49.0.1.840.0.201d4d0e609856f1e9fa489089d3ee1517d096e7.001.1","noaa_urn:oid:2.49.0.1.840.0.8a44a8979ccd54f92a35db6c01c43daaafdaa4bb.005.1","noaa_urn:oid:2.49.0.1.840.0.8a44a8979ccd54f92a35db6c01c43daaafdaa4bb.002.1","noaa_urn:oid:2.49.0.1.840.0.8a44a8979ccd54f92a35db6c01c43daaafdaa4bb.001.1","noaa_urn:oid:2.49.0.1.840.0.8a44a8979ccd54f92a35db6c01c43daaafdaa4bb.003.1","noaa_urn:oid:2.49.0.1.840.0.8a44a8979ccd54f92a35db6c01c43daaafdaa4bb.004.1","noaa_urn:oid:2.49.0.1.840.0.8a44a8979ccd54f92a35db6c01c43daaafdaa4bb.006.1","noaa_urn:oid:2.49.0.1.840.0.310240139040545b80868f62f2ea7ecf5b1451ee.002.1","noaa_urn:oid:2.49.0.1.840.0.310240139040545b80868f62f2ea7ecf5b1451ee.003.1","noaa_urn:oid:2.49.0.1.840.0.310240139040545b80868f62f2ea7ecf5b1451ee.004.1","noaa_urn:oid:2.49.0.1.840.0.5db15c5f9c6afdf6513f8d44e85f23e8c7bd7b7a.001.1","noaa_urn:oid:2.49.0.1.840.0.9951cc7a5b403610bfe9986bda2647789c79aacf.001.1","noaa_urn:oid:2.49.0.1.840.0.00ce4b41f16046c97bd76fdfd53e412dd5fe61b8.001.1","noaa_urn:oid:2.49.0.1.840.0.c44008e5313c1060fd05a003becdac76a95880c0.001.1","noaa_urn:oid:2.49.0.1.840.0.a6e0650c3222075599057ce2e812dba7e082bf9b.002.1","noaa_urn:oid:2.49.0.1.840.0.8ca1de0fa6f71cdb8d0dc8293c5387c8faa34825.001.1","noaa_urn:oid:2.49.0.1.840.0.8ca1de0fa6f71cdb8d0dc8293c5387c8faa34825.005.1","noaa_urn:oid:2.49.0.1.840.0.8ca1de0fa6f71cdb8d0dc8293c5387c8faa34825.004.1","noaa_urn:oid:2.49.0.1.840.0.8ca1de0fa6f71cdb8d0dc8293c5387c8faa34825.002.1","noaa_urn:oid:2.49.0.1.840.0.8ca1de0fa6f71cdb8d0dc8293c5387c8faa34825.003.1","noaa_urn:oid:2.49.0.1.840.0.16c58d2a12d6341819a77d03f021d23c53101f90.004.1","noaa_urn:oid:2.49.0.1.840.0.16c58d2a12d6341819a77d03f021d23c53101f90.003.1","noaa_urn:oid:2.49.0.1.840.0.16c58d2a12d6341819a77d03f021d23c53101f90.005.1","noaa_urn:oid:2.49.0.1.840.0.16c58d2a12d6341819a77d03f021d23c53101f90.001.1","noaa_urn:oid:2.49.0.1.840.0.16c58d2a12d6341819a77d03f021d23c53101f90.002.1","noaa_urn:oid:2.49.0.1.840.0.b97ca6a14a1edb14f81894cd575999c5a476ef62.001.1","noaa_urn:oid:2.49.0.1.840.0.b58ca7fce4d0ad253db9c2fa34889635fa81d240.001.1","noaa_urn:oid:2.49.0.1.840.0.b58ca7fce4d0ad253db9c2fa34889635fa81d240.002.1","noaa_urn:oid:2.49.0.1.840.0.13d2c6b57d6de597cf9950c8383fff4def48cc58.001.1","noaa_urn:oid:2.49.0.1.840.0.10266971fc45a981506e8898df90f5aa3447e2f2.001.1","noaa_urn:oid:2.49.0.1.840.0.10266971fc45a981506e8898df90f5aa3447e2f2.003.1","noaa_urn:oid:2.49.0.1.840.0.10266971fc45a981506e8898df90f5aa3447e2f2.002.1","noaa_urn:oid:2.49.0.1.840.0.892c94d9b3df6a67156fae5c9f2f5b1cec0fe0ec.002.1","noaa_urn:oid:2.49.0.1.840.0.892c94d9b3df6a67156fae5c9f2f5b1cec0fe0ec.001.1","noaa_urn:oid:2.49.0.1.840.0.a6e0650c3222075599057ce2e812dba7e082bf9b.001.1","noaa_urn:oid:2.49.0.1.840.0.92d671855f243f951257e7e76b994de22d2de280.001.1"] |
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 near O'Fallon?
Calamity.live data shows a weather event with CalamityScore 48/100, near O'Fallon (United States), based on data from noaa. Source: Calamity.live, a platform aggregating real-time data from 185 scientific monitoring sources.