Several areas in Luzon experienced cloudy skies and rainfall on Monday due to the shear line and the Northeast Monsoon (Amihan), the Philippine Atmospheric, Geophysical and Astronomical Services Administration (Pagasa) said.
Cagayan Valley, Nueva Ecija, Bulacan, Aurora, Rizal, and Laguna experienced cloudy skies with rain as a result of the Amihan.
In its 4 p.m. forecast on Sunday, Pagasa said the shear line caused cloudy conditions with scattered rains and isolated thunderstorms over Mimaropa, the Bicol Region, Western Visayas, Quezon, Northern Samar, and Eastern Samar.
The rest of the country saw partly cloudy to cloudy skies with isolated rain showers or thunderstorms from localized thunderstorm activity.
Pagasa warned that the weather in affected areas could trigger flash floods and landslides, especially in flood- and landslide-prone locations.
The Northeast Monsoon also affected Metro Manila, the Cordillera Administrative Region (CAR), the rest of Calabarzon, and other parts of Luzon, though no significant impact was reported in these areas.
State meteorologists said winds ranged from moderate to gale strength in northern Luzon, with coastal waters becoming rough to very rough, while the rest of the country experienced lighter winds and calmer seas.