PAGASA Warns 13 Areas in Philippines Face 'Danger' Heat Index of Up to 44°C on Monday

Key facts

• 13 areas will experience 'danger' level heat index on May 4, 2026, with values from 42°C to 44°C.
• Dagupan City, Pangasinan, records the highest forecast at 44°C.
• 61 areas, including two in Metro Manila, face 'extreme caution' heat index (33°C–41°C).
• Pasay City reached a 'danger level' heat index of 42°C on Sunday.
• Manila Mayor Isko Moreno Domagoso launched 'Oplan Misty' using water trucks to cool Taft Avenue.
• Manila municipal employees shift to a four-day workweek with strict hydration protocols for outdoor workers.
• PAGASA issued a thunderstorm watch for Metro Manila and surrounding provinces for a 12-hour window.
• Easterlies from the Pacific Ocean dominate the region, driving the heat and thunderstorms.

Danger-Level Heat Index Forecast for Monday

The Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) has warned that 13 areas across the country will experience a 'danger' level heat index on Monday, May 4, 2026. Based on its five-day heat index forecast, the affected locations will record heat index values ranging from 42°C to 44°C. Dagupan City in Pangasinan is expected to be the hottest, with a heat index of 44°C. Other areas include Laoag City, Ilocos Norte at 43°C, and Tuguegarao City, Cagayan at 42°C. The list also features MMSU in Batac, Ilocos Norte; San Jose, Occidental Mindoro; and Davao City, Davao del Sur, each at 42°C. Meanwhile, 61 areas—including two in Metro Manila—are forecast to experience 'extreme caution' heat index levels, defined as 33°C to 41°C. Tanay, Rizal is the lone area expected to fall under the 'caution' level, with a heat index of 32°C. Some areas may register 'not hazardous' heat index levels below 27°C.

Metro Manila Braces for a Week of Hazardous Heat

Metro Manila is expected to face a week of dangerous heat levels and localized thunderstorms as Easterlies from the Pacific Ocean dominate the region, state weather forecasters said Sunday. PAGASA projected that the heat index in Pasay City reached a 'danger level' of 42°C on Sunday. Ambient temperatures across the National Capital Region are forecast to range between 25°C and 36°C through 9 May, but high humidity will likely keep the perceived heat at hazardous levels. PAGASA also issued a thunderstorm watch for the metropolis and surrounding provinces, warning that severe localized thunderstorms are more likely to develop within a 12-hour window. 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°C in areas such as Laoag City and Tuguegarao City, while the southern regions may experience scattered rains and potential flash floods.

Manila City Launches 'Oplan Misty' and Adjusts Workweek

In response to the forecast, the City of Manila has implemented several mitigation measures. Mayor Francisco 'Isko Moreno' Domagoso directed the Manila City Disaster Risk Reduction and Management Department (MCDRRMD) to launch 'Oplan Misty,' which uses water trucks to spray a fine mist along Taft Avenue to cool public spaces. Additionally, the city has shifted municipal employees to a four-day workweek and mandated strict hydration protocols for outdoor frontliners, including traffic enforcers and police officers. Authorities advise citizens to remain hydrated and limit outdoor activities to avoid heat-caused illnesses during the day. Taking necessary precautions to avoid heat and sun exposure was also encouraged as the 'Agua de Mayo' (May rain showers) remains to arrive.

Thunderstorm Watch and Regional Variations

PAGASA's thunderstorm watch covers Metro Manila and surrounding provinces, indicating that severe localized thunderstorms are more likely to develop within a 12-hour window. This adds a layer of complexity to the week's weather, as the same Easterlies that bring intense heat also fuel convective storms. While the northern and central regions bake under dangerous heat indices, southern regions may experience scattered rains and potential flash floods. The dual threat of extreme heat and sudden thunderstorms underscores the need for public vigilance. PAGASA continues to monitor conditions and update forecasts accordingly. The agency's five-day heat index forecast also includes data for subsequent days, with 15 areas expected to hit 'danger' heat index on May 5, and 13 areas on May 2.

Public Health Advisories and Precautions

Authorities are urging the public to take the heat warnings seriously. Heat index at 'danger' level (42°C and above) poses a high risk of heat cramps, heat exhaustion, and even heat stroke with prolonged exposure. The 'extreme caution' level (33°C–41°C) still carries risk of heat-related illnesses. Citizens are advised to stay hydrated, limit outdoor activities during peak heat hours, and wear light clothing. The elderly, children, and those with pre-existing health conditions are particularly vulnerable. PAGASA's warnings come as the country experiences the tail end of the dry season, with the 'Agua de Mayo' (May rain showers) yet to arrive. The combination of high temperatures and high humidity creates a stifling environment that demands proactive measures from both government and individuals.

Outlook: Continued Heat and Thunderstorm Risk

The pattern of intense morning heat followed by isolated afternoon or evening rain is expected to persist throughout the week. may come in the form of rain, the overall risk of heat-related illnesses remains high. Manila's mitigation measures, including 'Oplan Misty' and the four-day workweek, may serve as a model for other local governments facing similar conditions. However, the effectiveness of these measures in reducing heat exposure will depend on sustained implementation and public compliance. As the week progresses, PAGASA will continue to update its heat index forecasts and thunderstorm watches. Residents in affected areas should stay informed and heed official advisories to minimize health risks.

The bottom line

• 13 areas will face 'danger' heat index of 42°C–44°C on May 4, led by Dagupan City at 44°C.
• 61 areas, including parts of Metro Manila, are under 'extreme caution' heat index (33°C–41°C).
• Manila launched 'Oplan Misty' and a four-day workweek to mitigate heat impact.
• PAGASA issued a thunderstorm watch for Metro Manila due to Easterlies.
• High humidity exacerbates perceived heat, making conditions hazardous despite ambient temperatures.
• Public advised to stay hydrated and limit outdoor activities; vulnerable groups at higher risk.