Masinloc, Zambales (PNA file photo by Joan Bondoc)

MANILA – Zambales province recorded the highest heat index so far this year at 53 degrees Celsius, classified as “extreme danger,” on Sunday.

The previous four days, it registered either 42 or 43 from the Iba station of state weather bureau Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA).

The province is forecast to have a lower heat index of 42 to 43 degrees on Monday and Tuesday.

Subic Bay, Olongapo; Muñoz, Nueva Ecija; and Dagupan, Pangasinan registered 47 degrees.

It was 43 degrees from the Quezon City and Pasay City stations.

Heat index is the apparent temperature felt by the body taking into account relative humidity, which is defined by experts as the measure of how much water vapor is in a water-air mixture compared to the maximum amount possible.

Only Baguio City remained on the “caution” level (27 to 32 degrees) as it averaged 28 degrees the past five days. (PNA)