Flooding is the most frequent and deadly natural disaster in the Philippines. Every year, monsoon rains, typhoons, and intense localised thunderstorms push rivers and drainage systems beyond their limits, inundating homes, farmland, and roads. PAGASA's flood warning system is designed to give communities enough lead time to act — but only if people understand what the alerts mean.

The PAGASA Flood Forecasting and Warning System

PAGASA operates the Flood Forecasting and Warning System for the Cagayan, Agno, Pampanga, Bicol, and other major river basins through its River Basin Control Center (RBCC). Warnings are issued based on water level readings from automated rain and river gauges placed at strategic points along each river system. When rainfall upstream causes water levels to rise rapidly, PAGASA issues colour-coded alerts that correspond to specific actions communities should take.

The Three-Level Alert System

Alert Level 1 — Yellow: Monitor and Prepare

A Yellow Alert means river water levels are rising and approaching the threshold at which flooding typically begins. This is your preparation window. Residents in low-lying areas and those living near riverbanks should begin moving valuables to higher floors, preparing their Go Bags, and identifying their evacuation route. Schools and offices near the river may begin early dismissal procedures. There is no immediate danger, but conditions can change rapidly — especially during a typhoon or when heavy rainfall continues upstream.

Alert Level 2 — Orange: Pre-emptive Evacuation

An Orange Alert means the river has reached or is approaching the level at which it historically overflows its banks. LGUs in the affected area should begin pre-emptive evacuation of the most vulnerable communities — those in the floodplain, along drainage canals, and in informal settlements built on low ground. Do not wait for the water to enter your home before leaving. Floodwater can rise faster than you can pack. Bring your Go Bag, important documents, medicines, and enough food and water for at least three days.

Alert Level 3 — Red: Forced Evacuation

A Red Alert is the most serious flood warning. The river is at critical level and flooding is either imminent or already occurring. If you have not yet evacuated, do so immediately. Do not attempt to drive through floodwater — even 30 centimetres of moving water can sweep a car off the road, and 60 centimetres can carry away an SUV. Do not walk through floodwater either; it may conceal open manholes, sharp debris, or live electrical wires. Move to the nearest evacuation centre or to the highest floor of a sturdy building and wait for rescue if you cannot leave safely.

Flash Floods: A Different and More Dangerous Threat

Flash floods are distinct from river flooding and are far more difficult to predict. They occur when intense, localised rainfall — often from a thunderstorm or the outer rainbands of a typhoon — overwhelms small streams and drainage systems within minutes. Flash floods are responsible for many of the most tragic deaths in Philippine typhoon events, including the 2011 Sendong disaster in Cagayan de Oro and Iligan, where hundreds of people were killed in the middle of the night with almost no warning.

If you live near a mountain stream, a small river, or at the base of a slope, be especially alert during heavy rainfall. Do not wait for an official warning if you can see or hear water rising rapidly. Move to high ground immediately.

Where to Find Official Flood Warnings

PAGASA publishes flood advisories on its official website (bagong.pagasa.dost.gov.ph), on its official Facebook page, and through the Philippine Information Agency. Your LGU's DRRMO will also broadcast alerts through community warning systems, text messages, and barangay officials. WeatherAlertPH aggregates these advisories and displays them on our Alerts page, updated every five minutes.