People should stay indoors and stay hydrated while outdoors as the heat index in Metro Manila might reach 39 to 41 degrees Celsius in the next three to four days, the state weather bureau said Monday.
The Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) defines heat index as human discomfort index that gives the "apparent" temperature, or what humans perceive or feel as the temperature affecting their body.
"As much as possible, if you're not going to do anything important outside, stay indoors," PAGASA weather forecaster Chris Perez told ABS-CBN's Teleradyo.
" Those who can't help to go outside because of the nature of their work, seek shade and drink water to keep hydrated," he added.
Easterlies continue to prevail and may bring cloudy skies with isolated rains over Metro Manila and the rest of the country, Perez said.
Last Friday, PAGASA logged a dangerous 53 degrees Celsius heat index in Dagupan City, Pangasinan, the highest temperature in the province this year.
Chief meteorological officer Jose Estrada Jr. of the PAGASA station in Dagupan said the high heat index was due to the easterlies prevailing at the east Pacific sea surface affecting the temperature in the province.
“Almost all of earth’s surface is now concreted thus heat is refracted, increasing the heat index,” he said.
The high heat index also results in localized thunderstorms, Estrada said.
He added the presence of southwest monsoon or “habagat” next month is expected to lower the temperature in the province.
“For now, let us make some mitigations like staying hydrated, avoiding direct sunlight, and rigorous activities under the sun,” he said.
Estrada warned that the high heat index may cause heat cramps, heat exhaustion, or even heat stroke that might endanger a person’s life.
He added the prevailing heat index also negatively affects the marine lives in fish pens and cages.