Manila: Two weather systems are predicted to bring rains across most of Luzon on Friday, according to the weather bureau. The southwesterly windflow is expected to trigger scattered rains and thunderstorms over the Ilocos, Cordillera, and Central Luzon regions. Meanwhile, the Cagayan Valley will be affected by scattered rains and thunderstorms due to the frontal system. The Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) has warned that moderate to heavy rains in these areas could result in flash floods or landslides.

According to Philippines News Agency, the southwesterly windflow will also cause isolated rain showers or thunderstorms over Metro Manila, Calabarzon, and Mimaropa. Localized thunderstorms may lead to isolated rain showers over the rest of the archipelago. The northern and eastern sections of northern Luzon will experience moderate winds and moderate seas, while elsewhere, winds are expected to be light to moderate with slight to moderate seas. As of 2 a.m., PAGASA reported that no low-pressure area is currently being monitored for possible tropical cyclone formation.

In addition to the rain forecast, PAGASA has also projected high heat index levels. The heat index is expected to peak at 46°C in Infanta, Quezon, with a 43°C heat index likely in Tuguegarao City, Cagayan; Baler (Radar), Aurora; Dipolog, Zamboanga del Norte; and Surigao City, Surigao del Norte. Further, the heat index could reach 42°C in Aparri, Cagayan; ISU Echague, Isabela; Casiguran, Aurora; CLSU Mu±oz, Nueva Ecija; Alabat, Quezon; Iloilo City; Dumangas, Iloilo; and Butuan City, Agusan del Norte. The heat index measures the temperature felt by the human body when relative humidity is combined with the actual air temperature. Under "danger" level conditions, ranging from 42°C to 51°C, the public is advised of increased risks of heat cramps, heat exhaustion, and heat stroke with prolonged exposure.