This alert expired on 4 September 2026 at 05:00 UTC. It is kept here as a record.
It is the 76th strongest of the 126 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 12:20AM EDT until September 4 at 1:00AM EDT by NWS Baltimore MD/Washington DC
Nearby, since 12 March 2026
- June 15, 2026 · score 22 · 4.8 km
- March 12, 2026 · score 43 · 8.0 km
- August 2, 2026 · score 28 · 8.4 km
How we know
One source: NOAA. Not yet confirmed by a second, independent source.
Our own score for this event is 16 out of 100, at 61 % 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 | 61% |
| Coordinates | 38.3344, -76.3970 |
| Nearest City | St. Charles (55 km) |
| Impact Tier | minor |
| Timestamp | 2026-09-04T04:20:00.000Z |
| Source | https://api.weather.gov/alerts/urn%3Aoid%3A2.49.0.1.840.0.05f4366d46cc18ab379a4d16ea3de9e1082f9938.001.1 |
Score Breakdown
Technical Details
| Event | Special Marine Warning |
| Urgency | Immediate |
| Certainty | Likely |
| AreaDesc | Tidal Potomac from Key Bridge to Indian Head MD; Tidal Potomac from Indian Head to Cobb Island MD; Tidal Potomac from Cobb Island MD to Smith Point VA; Chesapeake Bay from Drum Point MD to Smith Point VA; Tangier Sound and the inland waters surrounding Bloodsworth Island; Chesapeake Bay from North Beach to Drum Point MD; Chesapeake Bay from Drum Point MD to Smith Point VA; Choptank River to Cambridge MD and the Little Choptank River; Patuxent River to Broomes Island MD; Tangier Sound and the inland waters surrounding Bloodsworth Island and 2 more areas |
| Headline | Special Marine Warning issued September 4 at 12:20AM EDT until September 4 at 1:00AM EDT by NWS Baltimore MD/Washington DC |
| Expires | 2026-09-04T01:00:00-04:00 |
| SenderName | NWS Baltimore MD/Washington DC |
| HasExactCoords | true |
| MergedCount | 5 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.05f4366d46cc18ab379a4d16ea3de9e1082f9938.001.1","noaa_urn:oid:2.49.0.1.840.0.7fcc60d7a1ec10537cd7adf06ec6002be2c3fc49.001.1","noaa_urn:oid:2.49.0.1.840.0.bae28c608dc4b559fe09fb018021d1b94cb6e9c9.001.1","noaa_urn:oid:2.49.0.1.840.0.66b2b6d0a976dc6b0c24839ea420313b55fac435.001.1","noaa_urn:oid:2.49.0.1.840.0.adb87b55b347a97fbbb4b6316068dcd8279ba985.001.1"] |
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 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.