This alert expired on 18 June 2026 at 23:45 UTC. It is kept here as a record.
No stronger detection stands among the 47 recorded within 20 km of this point since 16 March 2026 — 15 others scored the same. Another comparable one was recorded here earlier the same day. 3 more were recorded here in the fortnight before it.
What the source measured
NOAA reported: Special Marine Warning issued June 18 at 5:47PM EDT until June 18 at 7:45PM EDT by NWS Charleston SC
An estimated 257,257 people live within 50 km of this point.
Nearby, since 16 March 2026
- June 21, 2026 · score 43 · 11.6 km
- July 12, 2026 · score 43 · 11.8 km
- August 11, 2026 · score 43 · 13.1 km
How we know
Confirmed by 6 independent sources, including NOAA.
Our own score for this event is 43 out of 100, at 90 % 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 | 90% |
| Coordinates | 32.0229, -80.7112 |
| Nearest City | Hilton Head Island (19 km) |
| Population Exposed | 257.3K within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-06-18T21:47:00.000Z |
| Source | https://api.weather.gov/alerts/merged_Special Marine Warning_noaa_urn:oid:2.49.0.1.840.0.1ddc6e90d77de969024f0ac82331176b |
Score Breakdown
Technical Details
| Event | Special Marine Warning |
| Urgency | Immediate |
| Certainty | Likely |
| AreaDesc | 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; 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 |
| Headline | Special Marine Warning issued June 18 at 5:47PM EDT until June 18 at 7:45PM EDT by NWS Charleston SC |
| Expires | 2026-06-18T19:45:00-04:00 |
| SenderName | NWS Charleston SC |
| HasExactCoords | true |
| MergedCount | 2 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.1ddc6e90d77de969024f0ac82331176bb000e025.001.1","noaa_urn:oid:2.49.0.1.840.0.bc81031301b1fcdcb2995dc3728b6436b560a5a7.001.1"] |
| Iem TypeSummary | D |
| Iem City | 4 E Marlow |
| Iem County | Effingham |
| Iem State | GA |
| Iem Wfo | CHS |
| Iem Remark | Power lines down across the road near 1980 Low Ground Road. Power outages were reported in the area. Time determined from radar data. |
| MergedSources | [{"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_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}] |
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 Island?
Calamity.live data shows a weather event with CalamityScore 43/100, near Hilton Head Island (United States), based on data from noaa. Source: Calamity.live, a platform aggregating real-time data from 185 scientific monitoring sources.