According to the Philippine Atmospheric, Geophysical, and Astronomical Services Administration (PAGASA), the southwest monsoon, locally known as habagat, continues to affect nearly the entire Luzon and Western Visayas, keeping weather bureaus on high alert as saturated soil levels make ongoing floods likely.
Rainfall Outlook and Affected Provinces
In a briefing held at 5 p.m. on Monday, August 10, PAGASA reported that moderate to intense rain may persist across more than a dozen areas for a 24-hour window. Zambales, Bataan, and Occidental Mindoro face the threat of being worst-hit by heavy to intense rainfall ranging between 100 and 200 millimeters from Monday afternoon through Tuesday afternoon, August 11. Meanwhile, Metro Manila, Ilocos Sur, La Union, Pangasinan, Benguet, Tarlac, Pampanga, Bulacan, Rizal, Cavite, and Batangas are expected to receive moderate to heavy rain between 50 and 100 millimeters.
Beyond the initial 24-hour period, the weather bureau expects the rainfall to ease further across most regions. From Tuesday afternoon, August 11, to Wednesday afternoon, August 12, moderate to heavy rain of 50 to 100 millimeters is forecast for La Union, Benguet, Pangasinan, Zambales, Bataan, and Occidental Mindoro. By Wednesday afternoon, August 12, through Thursday afternoon, August 13, that same level of moderate to heavy precipitation will likely narrow down to just Zambales, Bataan, and Occidental Mindoro. For Monday evening, scattered rain and thunderstorms are expected across remaining areas of Luzon and Western Visayas due to the continuing impact of the southwest monsoon.
Did You Know? PAGASA recorded Typhoon Peilou at 3,000 kilometers east of extreme Northern Luzon, moving east at a fast 35 kilometers per hour with maximum sustained winds of 75 kilometers per hour, though the weather bureau confirmed the storm is not expected to enter the Philippine Area of Responsibility.
Dam Levels and Disaster Casualties
Monday’s heavy downpours pushed Quezon City’s La Mesa Dam past its spilling level of 80.15 meters. PAGASA logged the water level at 80.17 meters at 5 p.m., while the Barangay North Fairview Disaster Risk Reduction and Management Committee reported an even higher measurement of 80.24 meters by 7 p.m. Whenever the La Mesa Dam overflows, communities situated near the Tullahan River—particularly in Quezon City, Caloocan City, Malabon City, Navotas City, and Valenzuela City—face heightened flood risks.
The National Disaster Risk Reduction and Management Council stated on Monday morning that the combined effects of the southwest monsoon, Tropical Depression Luis, and Tropical Storm Maymay (Kujira) have resulted in at least eight deaths, nine injuries, and one person reported missing following days of floods and landslides across Luzon. Meanwhile, PAGASA continues monitoring Tropical Storm Peilou outside the Philippine Area of Responsibility, alongside two to four tropical cyclones projected to develop or enter the region throughout August.
Expert Insight: As soil saturation peaks across vulnerable provinces, disaster management officials emphasize that receding rain does not immediately eliminate danger. Communities near overflowing waterways like the La Mesa Dam remain susceptible to secondary flooding hazards long after active downpours begin to taper off.
Frequently Asked Questions
Which provinces are expected to receive the heaviest rainfall from Monday afternoon to Tuesday afternoon?
According to PAGASA, Zambales, Bataan, and Occidental Mindoro are forecast to experience heavy to intense rainfall ranging from 100 to 200 millimeters.
What caused the La Mesa Dam to breach its spilling level?
Monday’s heavy downpours from the southwest monsoon caused the dam to exceed its 80.15-meter spilling threshold, reaching 80.17 meters according to PAGASA and 80.24 meters according to local barangay disaster committees.
Is Tropical Storm Peilou expected to make landfall in the Philippines?
No, PAGASA reported that Peilou is tracking away from the country at 35 kilometers per hour and is not expected to enter the Philippine Area of Responsibility.
How are local communities in your area preparing for ongoing monsoon rains and potential dam overflows?