This alert expired on 4 July 2026 at 23:00 UTC. It is kept here as a record.
It is the 8th strongest of the 108 detections recorded within 20 km of this point since 12 March 2026. Another comparable one was recorded here earlier the same day. 22 more were recorded here in the fortnight before it.
What the source measured
NOAA reported: Special Marine Warning issued July 4 at 6:25PM EDT until July 4 at 7:00PM EDT by NWS Baltimore MD/Washington DC
An estimated 2,817,310 people live within 50 km of this point.
Nearby, since 12 March 2026
- March 17, 2026 · score 52 · 2.3 km
- March 16, 2026 · score 52 · 2.3 km
- May 14, 2026 · score 52 · 2.9 km
How we know
Confirmed by 3 independent sources, including NOAA.
Our own score for this event is 52 out of 100, at 87 % confidence.
The score is ours, computed from intensity, exposed population and local history — not the source’s.
Event Data
| Type | Severe weather |
| Severity | medium |
| Calamity Score (ours) | 52 / 100 |
| Our confidence | 87% |
| Coordinates | 38.5244, -77.0632 |
| Nearest City | Saint Charles (14 km) |
| Population Exposed | 2.8M within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-07-04T22:25:00.000Z |
| Source | https://api.weather.gov/alerts/merged_Special Marine Warning_noaa_urn:oid:2.49.0.1.840.0.b402cb13deba1cd9bab2fb8a2a56bdd4 |
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 Cobb Island MD to Smith Point VA; Tidal Potomac from Key Bridge to Indian Head MD; Tidal Potomac from Indian Head to Cobb Island MD |
| Headline | Special Marine Warning issued July 4 at 6:25PM EDT until July 4 at 7:00PM EDT by NWS Baltimore MD/Washington DC |
| Expires | 2026-07-04T19:00:00-04:00 |
| SenderName | NWS Baltimore MD/Washington DC |
| HasExactCoords | true |
| MergedCount | 2 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.b402cb13deba1cd9bab2fb8a2a56bdd4d544436c.001.1","noaa_urn:oid:2.49.0.1.840.0.6b9144f890a268885cddd75e1c309fc3a5a4fd49.001.1"] |
| Iem TypeSummary | D |
| Iem City | 4 NE Corbin |
| Iem County | Caroline |
| Iem State | VA |
| Iem Wfo | AKQ |
| Iem Remark | Trees down On US-17 in the County of Caroline, in the vicinity of Pepmeier Hill Rd; Rt. 610N/S (Caroline County). |
| MergedSources | [{"id":"iem_D_38.300_-77.460_1783200600000","source":"iem","severity":"low","severityValue":25,"timestamp":1783200600000,"latitude":38.3,"longitude":-77.46},{"id":"iem_D_38.230_-77.330_1783199400000","source":"iem","severity":"low","severityValue":25,"timestamp":1783199400000,"latitude":38.23,"longitude":-77.33}] |
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 10 February 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.
Calamity.live data shows a weather event with CalamityScore 52/100, near Saint Charles (United States), based on data from noaa. Source: Calamity.live, a platform aggregating real-time data from 188 scientific monitoring sources.