QC flooded on Aug. 30 after nearly a week's rain fell in 3 hours —PAGASA

A severe thunderstorm on Saturday, August 30, 2025, drenched Quezon City with rainfall nearly equivalent to a week’s normal volume, triggering widespread flooding in several major roads and low-lying areas. 

According to PAGASA, the Science Garden Station in Quezon City recorded 134.2 millimeters of rain between 1:00 p.m. and 4:00 p.m. This amount is almost equal to a week’s worth of rain, based on the monthly normal of 568.5 mm.

PAGASA said the heaviest downpour occurred between 2:00 p.m. and 3:00 p.m., when rainfall intensity peaked at 96.6 to 105.0 mm per hour. 

This level corresponds to a 10- to 15-year return period based on the Science Garden Rainfall Intensity-Duration-Frequency (RIDF) Curve—enough to trigger flooding in susceptible parts of the city.

Floodwaters rose in multiple locations near creeks connected to the San Juan River system, which GeoRiskPH hazard maps classify as highly flood-prone. 

Affected areas included Mother Ignacia Avenue, Elliptical Road, Araneta Avenue, Katipunan Avenue, EDSA-Centris, and portions of Quezon Avenue.

In its assessment, PAGASA concluded that the localized thunderstorm over northern Metro Manila was severe enough to overwhelm drainage and waterways, leading to significant flooding across Quezon City.

The Quezon City local government unit (LGU) on Saturday said intense flooding occurred in Districts 1, 3, and 4 which caused inconvenience to the public.

It said 36 out of 142 barangays were affected by flooding.

The QC LGU said the amount of rainfall on Saturday was "phenomenal", exceeding the hourly amount that fell during Tropical Storm Ondoy in 2009.

Citing the preliminary analysis of the UP Resilience Institute and UP Noah Center which analyzed data from rain gauges and weather stations in Metro Manila of PAGASA and IRISEUP, the LGU said 121 mm of rainfall was recorded in one hour. During Tropical Storm Ondoy in 2009, the rainfall in one hour was recorded at 90 mm.

Meanwhile, 141 mm of rainfall was recorded in 24 hours last Saturday, the Quezon City Disaster Risk Reduction and Management Offices said.

The LGU said the city's drainage system was not able to deal with the big volume of rain water in such a short time.

However, the floods eventually subsided, it said. —Sherylin Untalan/KG, GMA Integrated News