This alert expired on 22 July 2026 at 02:45 UTC. It is kept here as a record.
No stronger detection stands among the 31 recorded within 20 km of this point since 11 March 2026 — 8 others scored the same. The last comparable one was on 23 June 2026.
What the source measured
NOAA reported: Flash Flood Warning issued July 21 at 7:45PM EDT until July 21 at 10:45PM EDT by NWS Boston/Norton MA
An estimated 1,590,607 people live within 50 km of this point.
Nearby, since 11 March 2026
- June 23, 2026 · score 52 · 9.6 km
- March 17, 2026 · score 52 · 11.7 km
- August 3, 2026 · score 46 · 18.6 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 80 % confidence.
The score is ours, computed from intensity, exposed population and local history — not the source’s.
Computed under scoring rules v1. Rows carrying other versions were judged by different rules and are not directly comparable.
Event Data
| Type | Severe Weather |
| Severity | Medium |
| Calamity Score (ours) | 52 / 100 |
| Our confidence | 80% |
| Coordinates | 41.7300, -71.1964 |
| Nearest City | Swansea (2 km) |
| Population Exposed | 1.6M within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-07-21T23:45:00.000Z |
| Source | https://api.weather.gov/alerts/urn:oid:2.49.0.1.840.0.88e4db972177fad8d98c999f1b9148e8b202f00e.001.1 |
Score Breakdown
Technical Details
| Event | Flash Flood Warning |
| Urgency | Immediate |
| Certainty | Likely |
| AreaDesc | Bristol, MA; Plymouth, MA; Bristol, RI; Newport, RI; Washington, RI |
| Headline | Flash Flood Warning issued July 21 at 7:45PM EDT until July 21 at 10:45PM EDT by NWS Boston/Norton MA |
| Expires | 2026-07-21T22:45:00-04:00 |
| SenderName | NWS Boston/Norton MA |
| HasExactCoords | true |
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 8 March 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 Swansea?
Calamity.live data shows a weather event with CalamityScore 52/100, near Swansea (United States), based on data from noaa. Source: Calamity.live, a platform aggregating real-time data from 185 scientific monitoring sources.