Key facts
- Alert
- Flash Flood Warning (severe)
- Issued by
- National Weather Service, Tiyan GU
- Areas
- Guam, GU
- Places
- Guam
- In effect
- until 3:30 AM GMT+10, Oct 18, 2026
- Detection
- Radar indicated
What the National Weather Service says
“Turn around, don't drown when encountering flooded roads.”
NWS Tiyan GU, Flash Flood Warning, 9:23 PM GMT+10 Oct 17, 2026 · official alert
“Most flood deaths occur in vehicles.”
NWS Tiyan GU, Flash Flood Warning, 9:23 PM GMT+10 Oct 17, 2026 · official alert
“Be especially cautious at night when it is harder to recognize the dangers of flooding.”
NWS Tiyan GU, Flash Flood Warning, 9:23 PM GMT+10 Oct 17, 2026 · official alert
What to do
Do not drive into flooded roads. The National Weather Service says to turn around, don't drown. Most flood deaths occur in vehicles.
Move to higher ground if water is rising near you. Stay away from small creeks and streams, underpasses and low-lying areas, which the warning says are at risk of flash flooding.
Be extra careful tonight. It is harder to recognize flood dangers in the dark. Just 6 inches of moving water can knock you down, and 1 foot can sweep a vehicle away.
Never drive around barricades. Check National Weather Service updates until the warning ends or is cancelled.
Context
FEMA flood-insurance records show 182 claims in Guam between 1980 and 2026. That count covers only insured properties, so it understates how often flooding has caused damage.
FEMA has made several disaster declarations for Guam in recent years. These include super typhoon Bavi on October 7, 2026, and super typhoon Sinlaku on June 30, 2026. Ground and drainage conditions after such storms may matter, but this warning is based on radar-indicated rain.
Updates
- The flash flood warning is no longer in effect.
- The National Weather Service updated the flash flood warning; it remains in effect until 3:30 AM GMT+10.
- NWS Tiyan GU issued the flash flood warning until 3:30 AM GMT+10.
History here
Guam County: 182 flood insurance claims in FEMA's National Flood Insurance Program records since 1980, most recent 2026.
Guam County: recent federal disaster declarations
- DR-4946 (2026): super typhoon bavi
- DR-4921 (2026): super typhoon sinlaku
- DR-4715 (2023): typhoon mawar
- DR-4433 (2019): typhoon wutip
- DR-4398 (2018): typhoon mangkhut
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Questions
- Is there a flash flood warning in Guam right now?
- Yes. The National Weather Service in Tiyan issued a Flash Flood Warning for Guam at 7:28 PM GMT+10 on Saturday, October 17, 2026. It runs until 3:30 AM GMT+10 on Sunday.
- How much rain has fallen in Guam?
- Radar indicated between 1 and 2 inches of rain had fallen at 728 PM. The National Weather Service says torrential rain will continue through the night.
- Which places in Guam could flood?
- The warning names Dededo, Tamuning, Yigo, Mangilao, Barrigada, Yona, Talofofo and Sinajana, among others. It also lists Inarajan, Asan, Merizo, Piti, Santa Rita and Umatac. Small creeks, streets, highways and underpasses are at risk.
Sources
- NWS Tiyan GU: Flash Flood Warning, Oct 17, 2026 weather.gov
- FEMA OpenFEMA: NFIP claims and disaster declarations fema.gov
How this page is made. The Herebeat Hazard Desk builds event pages from official U.S. government data (National Weather Service, USGS, FEMA). The text is written with AI from that data; every number and quote is checked against the official source automatically before publishing, and the page is updated when the agency updates the event. The official source is always the reference. Spotted a mistake? info@herebeat.app. About the Hazard Desk.