This alert expired on 18 June 2026 at 22:15 UTC. It is kept here as a record.
It is the 3rd strongest of the 41 detections recorded within 20 km of this point since 16 March 2026. The last comparable one was on 2 June 2026.
What the source measured
NOAA reported: Special Marine Warning issued June 18 at 5:20PM EDT until June 18 at 6:15PM EDT by NWS Charleston SC
An estimated 109,477 people live within 50 km of this point.
Nearby, since 16 March 2026
- July 27, 2026 · score 43 · 3.0 km
- June 2, 2026 · score 43 · 4.2 km
- June 24, 2026 · score 43 · 5.7 km
How we know
Confirmed by 12 independent sources, including NOAA.
Our own score for this event is 43 out of 100, at 89 % 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) | 43 / 100 |
| Our confidence | 89% |
| Coordinates | 32.2646, -80.5886 |
| Nearest City | Hilton Head (16 km) |
| Population Exposed | 109.5K within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-06-18T21:20:00.000Z |
| Source | https://api.weather.gov/alerts/merged_Special Marine Warning_noaa_urn:oid:2.49.0.1.840.0.bc81031301b1fcdcb2995dc3728b6436 |
Score Breakdown
Technical Details
| Event | Special Marine Warning |
| Urgency | Immediate |
| Certainty | Likely |
| AreaDesc | Coastal waters from South Santee River to Edisto Beach SC out 20 NM; Coastal waters from Edisto Beach SC to Savannah GA out 20 NM; Coastal waters from Edisto Beach SC to Savannah GA out 20 NM; Coastal waters from Savannah GA to Altamaha Sound GA out 20 nm, including Grays Reef National Marine Sanctuary |
| Headline | Special Marine Warning issued June 18 at 5:20PM EDT until June 18 at 6:15PM EDT by NWS Charleston SC |
| Expires | 2026-06-18T18:15:00-04:00 |
| SenderName | NWS Charleston SC |
| HasExactCoords | true |
| MergedCount | 2 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.bc81031301b1fcdcb2995dc3728b6436b560a5a7.001.1","noaa_urn:oid:2.49.0.1.840.0.ef895a5666373bec25d2f4fdaf3833b1eb05a5c0.001.1"] |
| Iem TypeSummary | D |
| Iem City | Robertville |
| Iem County | Jasper |
| Iem State | SC |
| Iem Wfo | CHS |
| Iem Remark | Jasper County Warning Point reported a tree down at the 10000 block of Cotton Hill Road. |
| MergedSources | [{"id":"iem_D_32.720_-80.800_1781816400000","source":"iem","severity":"low","severityValue":25,"timestamp":1781816400000,"latitude":32.72,"longitude":-80.8},{"id":"iem_D_32.840_-80.820_1781816940000","source":"iem","severity":"low","severityValue":25,"timestamp":1781816940000,"latitude":32.84,"longitude":-80.82},{"id":"iem_D_32.690_-80.850_1781816100000","source":"iem","severity":"low","severityValue":25,"timestamp":1781816100000,"latitude":32.69,"longitude":-80.85},{"id":"iem_D_32.480_-80.940_1781814720000","source":"iem","severity":"low","severityValue":25,"timestamp":1781814720000,"latitude":32.48,"longitude":-80.94},{"id":"iem_D_32.260_-80.900_1781814420000","source":"iem","severity":"low","severityValue":25,"timestamp":1781814420000,"latitude":32.26,"longitude":-80.9},{"id":"iem_D_32.090_-81.120_1781813340000","source":"iem","severity":"low","severityValue":25,"timestamp":1781813340000,"latitude":32.09,"longitude":-81.12},{"id":"iem_D_32.520_-81.270_1781813220000","source":"iem","severity":"low","severityValue":25,"timestamp":1781813220000,"latitude":32.52,"longitude":-81.27},{"id":"iem_D_32.690_-80.830_1781816220000","source":"iem","severity":"low","severityValue":25,"timestamp":1781816220000,"latitude":32.69,"longitude":-80.83},{"id":"iem_M_32.110_-80.840_1781815140000","source":"iem","severity":"low","severityValue":25,"timestamp":1781815140000,"latitude":32.11,"longitude":-80.84},{"id":"iem_D_32.260_-81.330_1781812320000","source":"iem","severity":"low","severityValue":25,"timestamp":1781812320000,"latitude":32.26,"longitude":-81.33},{"id":"iem_D_32.590_-81.200_1781813940000","source":"iem","severity":"low","severityValue":25,"timestamp":1781813940000,"latitude":32.59,"longitude":-81.2}] |
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.
Want to know when something happens near Hilton Head?
Calamity.live data shows a weather event with CalamityScore 43/100, near Hilton Head (United States), based on data from noaa. Source: Calamity.live, a platform aggregating real-time data from 185 scientific monitoring sources.