This alert expired on 4 September 2026 at 05:00 UTC. It is kept here as a record.
It is the 117th strongest of the 216 detections recorded within 20 km of this point since 17 March 2026. Another comparable one was recorded here earlier the same day.
What the source measured
NOAA reported: Special Marine Warning issued September 3 at 11:39PM EDT until September 4 at 1:00AM EDT by NWS Baltimore MD/Washington DC
An estimated 137,507 people live within 50 km of this point.
Nearby, since 17 March 2026
- July 21, 2026 · score 37 · 7.8 km
- August 3, 2026 · score 43 · 8.2 km
- May 27, 2026 · score 43 · 8.6 km
How we know
One source: NOAA. Not yet confirmed by a second, independent source.
Our own score for this event is 37 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) | 37 / 100 |
| Our confidence | 81% |
| Coordinates | 38.2889, -76.7751 |
| Nearest City | Saint Charles (37 km) |
| Population Exposed | 137.5K within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-09-04T03:39:00.000Z |
| Source | https://api.weather.gov/alerts/urn%3Aoid%3A2.49.0.1.840.0.1a818996a1faabaf502c7dec7e0e76060e564963.001.1 |
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; Tidal Potomac from Cobb Island MD to Smith Point VA |
| Headline | Special Marine Warning issued September 3 at 11:39PM 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 | 2 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.1a818996a1faabaf502c7dec7e0e76060e564963.001.1","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 37/100 (United States), based on data from noaa. Source: Calamity.live, a platform aggregating real-time data from 185 scientific monitoring sources.