Extreme northern Luzon and parts of Mindanao are expected to experience rainfall, while localized afternoon or evening thunderstorms may occur in the rest of the country over the next 24 hours, the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) said on Sunday, May 17.

PAGASA weather specialist Veronica Torres said the frontal system is affecting extreme northern Luzon, bringing rains particularly over Batanes and Babuyan Islands.

“Ang frontal system o stationary front ay salubungan ng dalawang hangin na merong magkaibang air mass. So, magkapareho yung lakas ng hangin kaya ito ay nagiging stationary o hindi gumagalaw (A frontal system or stationary front is where two air masses with different characteristics meet. The winds have similar strength, causing the system to become stationary or not move),” Torres said.

Improving weather conditions are expected in these areas by Monday, May 18, she added.

Meanwhile, the Intertropical Convergence Zone (ITCZ) is affecting southern Mindanao.

“Ito naman yung salubungan ng hangin galing northern at southern hemisphere. So, ito ang nakakaapekto sa may southern Mindanao at nagpapaulan sa may southern at kanlurang bahagi ng Mindanao (This is where winds from the northern and southern hemispheres meet. This affects southern Mindanao and brings rains to the southern and western parts of the region),” she said.

Scattered rains are expected over Zamboanga Peninsula, Sultan Kudarat, Sarangani, Lanao del Sur, Maguindanao del Norte, Basilan, and Tawi-Tawi.

Torres also said the low-pressure area being monitored in recent days has already dissipated.

For the rest of the country, including Metro Manila, generally fair weather conditions will prevail over the next three to five days, although localized thunderstorms may still develop in the afternoon or evening.

Heat index levels remain high across the country despite the presence of rain-bearing systems.

On Sunday, Metro Manila’s heat index is forecast at 41°C to 44°C, while Dipolog City in Zamboanga del Norte may reach up to 46°C.

Torres urged the public to remain cautious against flooding or landslides in areas that have experienced rainfall in recent days, despite the absence of a tropical cyclone or low-pressure area, as the frontal system, ITCZ, and localized thunderstorms may still bring moderate to heavy rain.