Metro Manila is expected to face a week of dangerous heat levels and localized thunderstorms as the easterlies from the Pacific Ocean dominate the region, state weather forecasters said Sunday.

The Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) projected the heat index in Pasay City will reach a “danger level” of 42 degrees Celsius.

While ambient temperatures across the capital are forecast to range between 25 and 36 degrees Celsius through 9 May, high humidity is expected to keep the perceived heat at hazardous levels.

Forecasters also issued a thunderstorm watch for the metropolis and surrounding provinces, warning that severe localized thunderstorms are likely to develop within 12-hour windows.

This pattern of intense morning heat followed by isolated afternoon or evening rain is expected to persist throughout the week.

Nationally, the heat index is forecast to peak at 43 degrees Celsius in Laoag City and Tuguegarao City. Southern regions may experience scattered rains and potential flash floods.

In response, Manila Mayor Francisco “Isko Moreno” Domagoso directed the city’s disaster risk department to launch “Oplan Misty,” using water trucks to spray a fine mist along Taft Avenue to cool public spaces.

The city has also shifted municipal employees to a four-day workweek and mandated strict hydration protocols for outdoor personnel, including traffic enforcers and police officers.

Authorities advised residents to stay hydrated and limit outdoor activities to avoid heat-related illnesses. Domagoso encouraged the public to take precautions as the region awaits the arrival of the “Agua de Mayo,” the traditional first rain of May.