This alert expired on 23 June 2026 at 09:15 UTC. It is kept here as a record.
It is the 10th strongest of the 77 detections recorded within 20 km of this point since 12 March 2026. The last comparable one was on 18 June 2026. 4 more were recorded here in the fortnight before it.
What the source measured
NOAA reported: Flash Flood Warning issued June 23 at 1:11AM EDT until June 23 at 5:15AM EDT by NWS Mount Holly NJ
An estimated 2,505,551 people live within 50 km of this point.
Nearby, since 12 March 2026
- July 21, 2026 · score 52 · 5.5 km
- July 29, 2026 · score 52 · 8.9 km
- March 12, 2026 · score 52 · 9.5 km
How we know
Confirmed by 2 independent sources, including NOAA.
Our own score for this event is 52 out of 100, at 84 % 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 | 84% |
| Coordinates | 40.9650, -74.5933 |
| Nearest City | Hopatcong Hills (7 km) |
| Population Exposed | 2.5M within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-06-23T05:11:00.000Z |
| Source | https://api.weather.gov/alerts/urn:oid:2.49.0.1.840.0.342e8eec3b8711edeb85a9e3e59702faae50938a.001.1 |
Score Breakdown
Technical Details
| Event | Flash Flood Warning |
| Urgency | Immediate |
| Certainty | Likely |
| AreaDesc | Morris, NJ; Sussex, NJ |
| Headline | Flash Flood Warning issued June 23 at 1:11AM EDT until June 23 at 5:15AM EDT by NWS Mount Holly NJ |
| Expires | 2026-06-23T05:15:00-04:00 |
| SenderName | NWS Mount Holly NJ |
| HasExactCoords | true |
| Iem TypeSummary | F |
| Iem City | Harrison |
| Iem County | Hudson |
| Iem State | NJ |
| Iem Wfo | OKX |
| Iem Remark | Flooded basement. |
| MergedSources | [{"id":"iem_F_40.750_-74.150_1782184440000","source":"iem","severity":"low","severityValue":25,"timestamp":1782184440000,"latitude":40.75,"longitude":-74.15}] |
Safety Information
During flooding: never walk, swim, or drive through floodwaters. Six inches of moving water can knock you down, and one foot of water can sweep away a vehicle. Move to higher ground if waters rise. After flooding, avoid contact with floodwater which may contain sewage, chemicals, or debris. Follow local emergency service guidance.
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 Hopatcong Hills (United States), based on data from noaa. Source: Calamity.live, a platform aggregating real-time data from 188 scientific monitoring sources.