The Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) has issued a critical weather advisory for Monday, December 8, 2025, as a trio of weather systems—a Low Pressure Area (LPA), the Shear Line, and the Northeast Monsoon (Amihan)—converge to bring widespread rainfall across the country. Public safety offices are on high alert as the risk of flash floods and landslides escalates, particularly in northern and eastern regions.
High-Risk Rainfall Outlook: Isabela Faces Intense Rain
The main concern remains the persistent, heavy rainfall expected over Luzon, driven primarily by the Shear Line affecting the eastern sections of Central and Southern Luzon.
- Today (December 8): The province of Isabela is placed under a Severe Rainfall Outlook, bracing for Heavy to Intense rain (100-200 mm). Nearby areas, including Cagayan, Apayao, Kalinga, Quirino, Aurora, and Quezon, are also forecast to experience Moderate to Heavy rain (50-100 mm).
- Persistent Threat (December 9 & 10): This intense rainfall threat will remain locked on Isabela for Tuesday and Wednesday, with the 100-200 mm forecast holding firm. The surrounding provinces, adding Mountain Province, Ifugao, and Nueva Vizcaya to the list, will continue to face Moderate to Heavy rainfall.
Meanwhile, the remnants of the former Tropical Depression “WILMA,” now a Low Pressure Area (LPA), is the source of the day’s moderate to heavy rain (50-100 mm) over Oriental Mindoro. The LPA is also responsible for the cloudy skies, scattered rains, and thunderstorms expected over MIMAROPA and Western Visayas, bringing a continued risk of flash floods and landslides.
Multiple Weather Systems Drive Regional Conditions
The rest of the archipelago is under the influence of other weather dynamics:
- Shear Line: In addition to the heavy rain in the north, it will bring cloudy skies with scattered rains and isolated thunderstorms to the Cordillera Administrative Region, Cagayan, Isabela, Nueva Vizcaya, Quirino, Aurora, and Quezon.
- Northeast Monsoon (Amihan): This cool, moist wind is causing cloudy skies with rains over Metro Manila, the rest of Cagayan Valley, and the rest of Central Luzon, also carrying a risk of flash floods. It will bring isolated light rains with no significant impact to the Ilocos Region.
- Easterlies: The Bicol Region is forecast to have cloudy skies with scattered rains and isolated thunderstorms due to the Easterlies.
- Localized Thunderstorms: Mindanao and the rest of Visayas will see partly cloudy to cloudy skies with isolated rain showers, where flash floods and landslides are possible during severe thunderstorms.
Mariners Cautioned as Seas Turn Rough
Sea conditions are becoming hazardous, especially for small seacraft. Rough to Very Rough coastal waters (2.8 to 4.5 meters) are expected along the eastern section of Luzon, where wind speeds are forecast to be Strong to Gale-force. The rest of Luzon will experience Moderate to Rough seas. Mariners in Visayas and Mindanao can expect Slight to Moderate conditions.
PAGASA stressed that rainfall forecasts may be significantly higher in mountainous areas, and previous rainfall could worsen the impact in vulnerable regions. Local disaster risk reduction and management offices are urged to take all necessary measures to protect life and property, and to monitor local Heavy Rainfall Warnings (which use real-time Doppler radar for immediate 3-hour forecasts) and Thunderstorm Advisories for site-specific information.