The Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) said the intense heat reached a "dangerous" level in 18 areas on Saturday, May 25.
PAGASA said that Aparri, Cagayan experienced a heat index of 48 degrees Celsius (°C) followed by Laoag City, Ilocos Norte with 47°C.
The heat index reached 45°C in Bacnotan, La Union; Iba, Zambales; and Butuan City, Agusan Del Norte.
Dagupan City, Pangasinan; Puerto Princesa City, Palawan; Dipolog, Zamboanga Del Norte
Zamboanga City, Zamboanga Del Sur experienced a 44°C heat index.
It reached 43°C in Sinait, Ilocos Sur; MMSU, Batac, Ilocos Norte; Calayan, Cagayan; Tacloban City, Leyte; Maasin, Southern Leyte; Cotabato City, Maguindanao; and Surigao City, Surigao Del Norte while Catarman, Northern Samar; and Borongan, Eastern Samar logged a heat index of 42°C.