This alert expired on 30 August 2026 at 08:30 UTC. It is kept here as a record.
It is the 13th strongest of the 27 detections recorded within 20 km of this point since 14 April 2026. The last comparable one was on 6 August 2026.
What the source measured
NOAA reported: Flash Flood Warning issued August 30 at 5:33PM ChST until August 30 at 6:30PM ChST by NWS Tiyan GU
An estimated 120,043 people live within 50 km of this point.
Nearby, since 14 April 2026
- August 30, 2026 · score 43 · 0.0 km
- July 5, 2026 · score 43 · 8.3 km
- August 6, 2026 · score 43 · 17.4 km
How we know
One source: NOAA. Not yet confirmed by a second, independent source.
Our own score for this event is 37 out of 100, at 82 % 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) | 37 / 100 |
| Our confidence | 82% |
| Coordinates | 13.5175, 144.7894 |
| Nearest City | Tamuning-Tumon-Harmon Village (3 km) |
| Population Exposed | 120.0K within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-08-30T07:33:00.000Z |
Score Breakdown
Technical Details
| Event | Flash Flood Warning |
| Urgency | Immediate |
| Certainty | Likely |
| AreaDesc | Guam, GU |
| Headline | Flash Flood Warning issued August 30 at 5:33PM ChST until August 30 at 6:30PM ChST by NWS Tiyan GU |
| Expires | 2026-08-30T18:30:00+10:00 |
| SenderName | NWS Tiyan GU |
| 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 37/100, near Tamuning-Tumon-Harmon Village (GU), based on data from noaa. Source: Calamity.live, a platform aggregating real-time data from 191 scientific monitoring sources.