This alert expired on 4 September 2026 at 21:30 UTC. It is kept here as a record.
It is the 92nd strongest of the 143 detections recorded within 20 km of this point since 12 March 2026. Another comparable one was recorded here earlier the same day.
What the source measured
NOAA reported: Special Marine Warning issued September 4 at 5:02PM EDT until September 4 at 5:30PM EDT by NWS Baltimore MD/Washington DC
An estimated 3,108,793 people live within 50 km of this point.
Nearby, since 12 March 2026
- March 17, 2026 · score 52 · 1.3 km
- March 16, 2026 · score 52 · 1.3 km
- July 18, 2026 · score 52 · 2.4 km
How we know
One source: NOAA. Not yet confirmed by a second, independent source.
Our own score for this event is 46 out of 100, at 81 % 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) | 46 / 100 |
| Our confidence | 81% |
| Coordinates | 38.5515, -77.0762 |
| Nearest City | Saint Charles (13 km) |
| Population Exposed | 3.1M within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-09-04T21:02:00.000Z |
| Source | https://api.weather.gov/alerts/urn%3Aoid%3A2.49.0.1.840.0.0244bab26854e1ebb69c3150d8d4f0306a25e7c9.001.1 |
Score Breakdown
Technical Details
| Event | Special Marine Warning |
| Urgency | Immediate |
| Certainty | Likely |
| AreaDesc | Tidal Potomac from Indian Head to Cobb Island MD; Tidal Potomac from Key Bridge to Indian Head MD; Tidal Potomac from Indian Head to Cobb Island MD |
| Headline | Special Marine Warning issued September 4 at 5:02PM EDT until September 4 at 5:30PM EDT by NWS Baltimore MD/Washington DC |
| Expires | 2026-09-04T17:30:00-04:00 |
| SenderName | NWS Baltimore MD/Washington DC |
| HasExactCoords | true |
| MergedCount | 2 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.0244bab26854e1ebb69c3150d8d4f0306a25e7c9.001.1","noaa_urn:oid:2.49.0.1.840.0.2a1b0d9e97bd99eeef2b08d133d10a170afc5cb1.001.1"] |
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 near Saint Charles?
Calamity.live data shows a weather event with CalamityScore 46/100, near Saint Charles (United States), based on data from noaa. Source: Calamity.live, a platform aggregating real-time data from 185 scientific monitoring sources.