Flash Flood Warning issued for Southwestern Guam

Source: NOAA · Guam

This alert is no longer in effect.

NOAA issued it on August 30, 2026, 3 weeks ago. Warnings of this kind stay in effect for hours to a few days, so this page is a historical record of what was issued, not a current warning. For conditions where you are right now, check weather.gov (US), weather.gc.ca (Canada), the Met Office (UK), or the Bureau of Meteorology (Australia).

Areazine synthesizes this NWS weather alert directly from NOAA's official public data feed. See our methodology for full source attribution and refresh cadence.

NWS Tiyan GU has issued a Flash Flood Warning for southwestern coasts of Guam until 10:30 PM ChST due to heavy rain and ongoing flash flooding.

The weather record, at a glance

Record type
Flash Flood Warning
Affected area
Guam
Issued
August 30, 2026
Issuing authority
NWS Tiyan GU

Flood notices turn on location and timing. Treat the named area as this record's scope; do not assume nearby counties, parishes, or waterways were included.

Record status: historical. It was issued 3 weeks ago; use the issuing agency's live warning service for current conditions in Guam.

Alert Details

Flash Flood Warning issued by NWS Tiyan GU. Effective from August 30, 2026 at 7:35 PM ChST until August 30, 2026 at 10:30 PM ChST. Severity: Severe. Urgency: Immediate. Certainty: Likely.

Affected Areas

Southwestern coasts of Guam, including Merizo, Piti, Santa Rita, Umatac, Apra Harbor, and Naval Base Guam.

What You Should Do

Turn around, don't drown when encountering flooded roads. Most flood deaths occur in vehicles.

Expected Conditions

Doppler radar indicated heavy rain across the warned area. Additional rainfall amounts of 2 to 3 inches are possible. Flash flooding caused by heavy rain is ongoing or expected to begin shortly. Impacts include flash flooding of small creeks and streams, urban areas, highways, streets and underpasses as well as other poor drainage and low-lying areas.

Timeline

Alert effective August 30, 2026 at 7:35 PM ChST. Expires and ends August 30, 2026 at 10:30 PM ChST.

Original source: NOAA Official Notice ↗

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Elsewhere in the country: similar length or severity timing 8

Two cross-category peer sets, both computed from Areazine's own archive: notices with a similar body length, and notices near the same severity and agency date. These are drawn from other categories, not the same-feed Related list above.

What People Ask

Questions readers often have about this NWS weather alert.

What is this NWS weather alert about?
NWS Tiyan GU has issued a Flash Flood Warning for southwestern coasts of Guam until 10:30 PM ChST due to heavy rain and ongoing flash flooding.
Which agency issued this alert?
This alert was issued by NOAA. The original notice is available at the source link at the bottom of this article.
How severe is this alert?
This alert is classified as "high" severity. Take precautions and monitor for updates.
What area is affected?
This alert affects Guam. Check with NOAA for the most current geographic scope.
Where can I find more Weather Alerts updates?
Browse the full Weather Alerts feed on Areazine at areazine.com/weather/ for the latest updates from NOAA and other agencies.