This alert expired on 14 August 2026 at 01:45 UTC. It is kept here as a record.
No stronger detection stands among the 18 recorded within 20 km of this point since 2 June 2026 — 8 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 August 13 at 7:45PM EDT until August 13 at 9:45PM EDT by NWS Charleston SC
An estimated 109,477 people live within 50 km of this point.
Nearby, since 2 June 2026
- July 12, 2026 · score 43 · 11.3 km
- June 21, 2026 · score 43 · 13.5 km
- June 2, 2026 · score 43 · 15.3 km
How we know
Confirmed by 8 independent sources, including NOAA.
Our own score for this event is 43 out of 100, at 91 % 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 | 91% |
| Coordinates | 32.0930, -80.5446 |
| Nearest City | Hilton Head Island (21 km) |
| Population Exposed | 109.5K within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-08-13T23:45:00.000Z |
| Source | https://api.weather.gov/alerts/merged_Special Marine Warning_noaa_urn:oid:2.49.0.1.840.0.34b2f5b4e815219ad7a4647acb6be1e6 |
Score Breakdown
Technical Details
| Event | Special Marine Warning |
| Urgency | Immediate |
| Certainty | Likely |
| AreaDesc | Charleston Harbor; Coastal waters from South Santee River to Edisto Beach SC out 20 NM; Coastal waters from Savannah GA to Altamaha Sound GA out 20 nm, including Grays Reef National Marine Sanctuary; Waters from Savannah GA to Altamaha Sound GA extending from 20 to 60 NM |
| Headline | Special Marine Warning issued August 13 at 7:45PM EDT until August 13 at 9:45PM EDT by NWS Charleston SC |
| Expires | 2026-08-13T21:45:00-04:00 |
| SenderName | NWS Charleston SC |
| HasExactCoords | true |
| MergedCount | 2 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.34b2f5b4e815219ad7a4647acb6be1e692eb0dc3.001.1","noaa_urn:oid:2.49.0.1.840.0.5b04f27c1dd8ac40050026bbe2f32ddd04fa5a6f.001.1"] |
| Iem TypeSummary | I |
| Iem Magnitude | 116 |
| Iem Unit | F |
| Iem City | Marine Corps Air Statio |
| Iem County | Beaufort |
| Iem State | SC |
| Iem Wfo | CHS |
| Iem Remark | Peak heat index of 116 degrees at Beaufort Marine Corps Air Station (KNBC). |
| MergedSources | [{"id":"iem_D_31.970_-81.220_1786659180000","source":"iem","severity":"low","severityValue":25,"timestamp":1786659180000,"latitude":31.97,"longitude":-81.22},{"id":"iem_D_31.980_-81.220_1786659180000","source":"iem","severity":"low","severityValue":25,"timestamp":1786659180000,"latitude":31.98,"longitude":-81.22},{"id":"iem_D_31.940_-81.310_1786658820000","source":"iem","severity":"low","severityValue":25,"timestamp":1786658820000,"latitude":31.94,"longitude":-81.31},{"id":"iem_D_32.030_-81.270_1786658100000","source":"iem","severity":"low","severityValue":25,"timestamp":1786658100000,"latitude":32.03,"longitude":-81.27},{"id":"iem_G_32.010_-81.130_1786649880000","source":"iem","severity":"low","severityValue":25,"timestamp":1786649880000,"latitude":32.01,"longitude":-81.13},{"id":"iem_D_32.460_-80.990_1786658700000","source":"iem","severity":"low","severityValue":25,"timestamp":1786658700000,"latitude":32.46,"longitude":-80.99},{"id":"iem_I_32.490_-80.700_1786654560000","source":"iem","severity":"low","severityValue":25,"timestamp":1786654560000,"latitude":32.49,"longitude":-80.7}] |
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.