Thirty-six out of 142 barangays in Quezon City were swamped by Ondoy (2009)-like flooding on Saturday, despite the local government’s Drainage Master Plan crafted with the University of the Philippines–Resilience Institute to address the perennial problem of baha.

The local government and the weather bureau both confirmed that “the an hour of record-breaking rainfall exceeded the rain water levels experienced during Storm ‘Ondoy’ in 2009.”

“Intense floods were experienced in some areas in Quezon City this afternoon especially in Districts 1, 3, and 4, which resulted in inconvenience to the public,” the city government said in an official statement, adding that Saturday’s rainfall was “phenomenal.”

“Sa preliminary analysis ng UP Resilience Institute at UP NOAH Center batay sa rain gauges at weather stations sa Metro Manila ng PAGASA at IRISEUP ng QC government, mailalarawan bilang ‘phenomenal’ o pambihira ang pag-ulan kanina na ang pinakabulto ay naitala sa Quezon City at Nangka, Marikina,” the LGU added.

According to the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA), rainfall data from the Science Garden monitoring station in Quezon City showed a total of 135.6 millimeters (mm) of rain fell between 8 a.m. on Aug. 30 and 8 a.m. on Aug. 31. The heaviest downpour was recorded from 2 p.m. to 5 p.m. on Saturday, with 116 mm of rainfall—classified as “intense to torrential.” This volume caused water levels to rise rapidly, triggering flash floods in low-lying and flood-prone areas.

PAGASA noted that unlike tropical cyclones, thunderstorms are highly localized and develop quickly, making them more difficult to forecast. Thunderstorm advisories are issued only two to three hours before expected rainfall.

While the flooding was severe, the agency observed that waters receded faster than during Typhoon Ondoy in 2009, which unleashed more than 300 mm of rain within just six hours, leading to widespread and prolonged inundation across Metro Manila.

The Quezon City government explained that Saturday’s “phenomenal” rainfall overwhelmed its drainage system, causing flooding even in areas not usually prone to it. However, floodwaters quickly subsided due to ongoing declogging operations by the Department of Engineering. The Department of Sanitation and Cleanup Works was also deployed to clear debris washed into drainage channels.

In October 2024, the city launched the “Tanggal Bara, Iwas Baha” program, directing all 142 barangays to prioritize the cleanup of clogged drainage systems, sewers, manholes, and interceptors to support citywide and national flood mitigation efforts.

Despite this, tons of basura still flooded streets in Barangays Del Monte, Masambong, Bagong Silangan, Doña Imelda, Roxas, Tatalon, and Apolonio Samson during Saturday’s downpour.

The city said its Drainage Master Plan remains focused on modernizing existing systems to cope with worsening flooding challenges brought about by extreme weather conditions.