This alert expired on 21 July 2026 at 17:30 UTC. It is kept here as a record.
It is the 10th strongest of the 82 detections recorded within 20 km of this point since 12 March 2026. The last comparable one was on 6 July 2026.
What the source measured
NOAA reported: Flash Flood Warning issued July 21 at 10:25AM EDT until July 21 at 1:30PM EDT by NWS Upton NY
An estimated 3,029,668 people live within 50 km of this point.
Nearby, since 12 March 2026
- March 12, 2026 · score 52 · 4.4 km
- June 23, 2026 · score 52 · 5.5 km
- July 28, 2026 · score 52 · 9.3 km
How we know
One source: NOAA. Not yet confirmed by a second, independent source.
Our own score for this event is 52 out of 100, at 81 % 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 | 81% |
| Coordinates | 40.9167, -74.6090 |
| Nearest City | Hopatcong Hills (6 km) |
| Population Exposed | 3.0M within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-07-21T14:25:00.000Z |
| Source | https://api.weather.gov/alerts/merged_Flash Flood Warning_noaa_urn:oid:2.49.0.1.840.0.3655bac8d9df3935575e943879ef01b3 |
Score Breakdown
Technical Details
| Event | Flash Flood Warning |
| Urgency | Immediate |
| Certainty | Likely |
| AreaDesc | Bergen, NJ; Essex, NJ; Passaic, NJ; Sussex, NJ; Warren, NJ |
| Headline | Flash Flood Warning issued July 21 at 10:25AM EDT until July 21 at 1:30PM EDT by NWS Upton NY |
| Expires | 2026-07-21T13:30:00-04:00 |
| SenderName | NWS Upton NY |
| HasExactCoords | true |
| MergedCount | 2 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.3655bac8d9df3935575e943879ef01b33bf5884a.001.1","noaa_urn:oid:2.49.0.1.840.0.339a7c80414aa402369cc58dab962a1b69544404.001.1"] |
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.