This alert is in force until 1 September 2026, 07:15 UTC.
It is the strongest of the 8 detections recorded within 20 km of this point since 28 March 2026. The last comparable one was on 17 April 2026.
What the source measured
NOAA reported: Flash Flood Warning issued September 1 at 12:21AM AST until September 1 at 3:15AM AST by NWS San Juan PR
An estimated 1,203,539 people live within 50 km of this point.
How we know
One source: NOAA. Not yet confirmed by a second, independent source.
Our own score for this event is 46 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) | 46 / 100 |
| Our confidence | 81% |
| Coordinates | 18.0619, -65.9662 |
| Nearest City | Humacao (17 km) |
| Population Exposed | 1.2M within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-09-01T04:21:00.000Z |
| Source | https://api.weather.gov/alerts/urn%3Aoid%3A2.49.0.1.840.0.a027102de1c0a8039a778171a95e992367ae1869.001.1 |
Score Breakdown
Technical Details
| Event | Flash Flood Warning |
| Urgency | Immediate |
| Certainty | Likely |
| AreaDesc | Arroyo, PR; Maunabo, PR; Patillas, PR; Yabucoa, PR |
| Headline | Flash Flood Warning issued September 1 at 12:21AM AST until September 1 at 3:15AM AST by NWS San Juan PR |
| Expires | 2026-09-01T03:15:00-04:00 |
| SenderName | NWS San Juan PR |
| 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 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 46/100, near Humacao (Puerto Rico), based on data from noaa. Source: Calamity.live, a platform aggregating real-time data from 188 scientific monitoring sources.