Heavy monsoon rains have affected more than 16,000 residents in Ilocos Sur and pushed major river systems near critical levels across Northern Luzon, provincial emergency officials and weather forecasters reported.

According to the Ilocos Sur Emergency Operations Center, at least 4,709 families, or 16,420 individuals, across 16 local government units have felt the impact of the southwest monsoon, locally known as habagat.

As of 31 August, 150 families had evacuated their homes, with 93 families staying in evacuation centers and 57 sheltering elsewhere.

The persistent rains have partially damaged 12 houses and left roads impassable in eight municipalities. Flooding was reported in seven municipalities, while power outages affected three towns.

The provincial government has begun distributing relief, delivering 85 food packs, 85 hygiene kits, 12 family kits, and 12 shelter repair kits to impacted communities.

State weather bureau Philippine Atmospheric, Geophysical and Astronomical Services Administration warned that the southwest monsoon will continue bringing heavy rains across parts of Northern and Central Luzon through 3 September, posing significant risks of flooding and landslides.

Benguet is expected to bear the brunt of the weather system, with 100 to 200 millimeters of rainfall forecast through 1 September.

Up to 100 millimeters of rain is projected across Ilocos Sur, Ilocos Norte, La Union, Pangasinan, Batanes, Abra, Apayao, Kalinga, Mountain Province, Tarlac, Pampanga, Zambales and Bataan.

Forecasters warned that the deluge will worsen already saturated grounds. Rain estimates of 100 to 200 millimeters remain in the forecast for Benguet, Zambales, Bataan, and Occidental Mindoro through 3 September, with lighter totals expected over adjacent provinces, including Cavite and Batangas.

Swollen rivers present an immediate hazard. Water levels along the entire stretch of the Abra River and its tributaries were approaching alert levels, threatening low-lying communities in Vigan, Bantay, and Santa in Ilocos Sur, as well as several towns in Abra.

Flooding also persists along the Agno River Basin in Pangasinan.

Water levels at key monitoring stations along the Lower Agno, Sinocalan, and Bugallon rivers remained above critical thresholds, threatening sustained inundation in Bayambang, Calasiao, Dagupan City, and surrounding municipalities. Minor coastal flooding is also possible in seaside areas along Lingayen Gulf.