Iba in Zambales recorded the highest heat index level yet - 53 degrees Celsius on Sunday - while 36 areas face dangerous levels of heat on Monday, according to weather bureau PAGASA.

Iba’s record 53 degrees Celsius heat index came after four straight days of registering only 42-43 degrees heat index. Temperatures are expected to drop back to 42 degrees Celsius heat index on Monday.

'Extremely dangerous': 53 degrees Celsius heat index recorded in Iba, Zambales

Dagupan City in Pangasinan remains one of the hottest areas in the country, with an expected heat index of 47 degrees Celsius on Monday, followed by Aparri in Cagayan with 46 degrees Celsius. 

Dagupan faces 48-degree scorcher for 2nd day

Three areas are forecast to register 45-degree heat index today: Laoag City, Tuguegarao City and Baler, Aurora. 

Six areas will experience 44-degree heat index today: Casiguran, Aurora; Sinait, Ilocos Sur, Dumangas, Iloilo; Aborlan, Palawan; San Jose, Occidental Mindoro, and Coron, Palawan.

The following areas are also facing extreme heat levels on Monday: 

NAIA Pasay City, Metro Manila - 43 degrees C

Science Garden, Quezon City, Metro Manila - 42 degrees C

MMSU, Batac, Ilocos Norte - 43 degrees C

NVSU Bayombong, Nueva Vizcaya - 43 degrees C

Clark Airport (DMIA), Pampanga - 42 degrees C

CLSU Munoz, Nueva Ecija - 42 degrees C

Cubi Pt., Subic Bay, Olongapo City - 42 degrees C

Sangley Point, Cavite - 42 degrees C

Ambulong, Tanauan, Batangas - 43 degrees C

Puerto Princesa City, Palawan - 43 degrees C

Legazpi City, Albay - 42 degrees C

Virac (Synop), Catanduanes - 43 degrees C

CBSUA-Pili, Camarines Sur - 42 degrees C

Roxas City, Capiz - 42 degrees C

Mambusao, Capiz - 42 degrees C

Iloilo City, Iloilo - 43 degrees C

La Granja, La Carlota, Negros Occidental - 42 degrees C

Guiuan, Eastern Samar - 43 degrees C

Dipolog, Zamboanga del Norte - 42 degrees C

Zamboanga City, Zamboanga del Sur - 43 degrees C

Davao City, Davao del Sur - 42 degrees C

Butuan, Augean del Norte - 42 degrees C

An Intertropical Convergence Zone, meanwhile, continues to affect southern Mindanao, bringing cloudy skies with scattered rainshowers and thunderstorms in Caraga and Davao region.

A state weather forecaster earlier said unusually hot weather in the Philippines is expected to last until mid-May.

The months of March, April and May are typically the hottest and driest time of the year, but this year's conditions have been exacerbated by the El Nino weather phenomenon.

"All places in the country, not necessarily just Metro Manila, are expected to have hotter temperatures until the second week of May," Glaiza Escullar of the state weather forecaster told AFP.

"There is a possibility that the areas will exceed those temperatures being measured today until the second week of May."

Philippines to endure extreme heat until mid-May

Global temperatures hit record highs last year, and the United Nations' weather and climate agency said Tuesday that Asia was warming at a particularly rapid pace.

The Philippines ranks among the countries most vulnerable to the impacts of climate change.