About 33 areas across the country are expected to experience a dangerous level of heat index on Sunday, according to Philippine Atmospheric, Geophysical, and Astronomical Services Administration (PAG-ASA).

A heat index of 42°C to 51°C falls under the "danger" category, based on PAGASA's classification, and would likely cause heat cramps and heat exhaustion, while heat stroke is probable with continued heat or sun exposure.

In its latest forecast, the state weather bureau said Dagupan City, Pangasinan and Aparri, Cagayan will experience the highest temperature hitting 47°C.

Meanwhile, three areas will reach 45°C: Laoag City, Ilocos Norte; Iba, Zambales; and the Central Bicol State University of Agriculture (CBSUA) in Pili, Camarines Sur.

This is followed by areas to experience a 45°C temperature: Bocnotan, Ilocos Sur; Legazpi City, Albay; Virac, Catanduanes; Dumangas, Iloilo; and Butuan City, Agusan del Norte.

Nine areas will be under 44°C: MMSU in Batac, Ilocos Norte; Tuguegarao City in Cagayan; Isabela State University in Echague, Isabela; Cubi Pt. in Subic Bay, Olongapo City; Puerto Princesa City in Palawan; Aborlan in Palawan; La Granja in La Carlota, Negros Occidental; Catarman in Northern Samar; and Cotabato City in Maguindanao.

The following areas are seen to experience 42°C heat index: Ninoy Aquino International Airport (NAIA) in Pasay; Sinait in Ilocos Sur; Clark International Airport in Pampanga; Central Luzon State University (CLSU) in Muñoz, Nueva Ecija; Casiguran in Aurora; Sangley Point in Cavite; Ambulong in Tanauan, Batangas; Infanta in Quezon; Alabat in Quezon; San Jose in Occidental Mindoro; Aborlan and Cuyo in Palawan; Daet in Camarines Norte; Masbate City in Masbate; Iloilo City in Iloilo; Dipolog in Zamboanga del Norte; and Zamboanga City in Zamboanga del Sur.