Manila: The Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) on Saturday warned of dangerous heat index levels in 31 areas. In its 4 a.m. forecast, PAGASA indicated that temperatures in these areas may feel as high as 46°C due to the combination of air temperature and relative humidity. According to Philippines News Agency, the areas identified with potentially hazardous heat indices include NAIA Pasay City with 42°C, Laoag in Ilocos Norte at 43°C, and Tayabas in Quezon reaching up to 45°C. Sangley Point in Cavite is forecasted to experience the highest heat index of 46°C. Other areas such as Aparri in Cagayan and Butuan City in Agusan del Norte may feel temperatures of 44°C. PAGASA explained that the heat index reflects what the temperature feels like to the human body when relative humidity is factored in with the air temperature. Consequently, the weather bureau advised the public to limit outdoor activities, especially during midday, and to stay hydrated by drinking plenty of water. It is recommended for people venturing outside to use protective measures such as umbrellas, hats, and sleeved clothing. In addition to the heat advisory, PAGASA noted that the easterlies will bring partly cloudy to cloudy skies with isolated rain showers or thunderstorms across the country, except for Batanes, where scattered rains and thunderstorms are expected due to a frontal system. The entire archipelago will experience light to moderate winds and slight to moderate sea conditions.