‘Danger level’ heat index forecast for 33 areas; Habagat to bring rain to Luzon

Rains are expected in parts of Luzon on Monday, June 2, 2025, due to the Southwest Monsoon or Habagat, but the heat index is also expected to reach the "danger level" in 33 areas across the country, PAGASA said Sunday.

According to the state weather bureau's forecast, 50 millimeters to 100 millimeters of rainfall is expected in Ilocos Norte, Ilocos Sur, Pangasinan, La Union, Abra, Batanes, Babuyan Islands, Zambales, and Bataan.

“Forecast rainfall may be higher in mountainous and elevated areas. Moreover, impacts in some areas may be worsened by significant antecendent rainfall,” the advisory read.

Cloudy skies with scattered rains are also expected in Metro Manila, the Cordillera Administrative Region (CAR), Calabarzon, Palawan, Occidental Mindoro, Oriental Mindoro, and the rest of central Luzon.

The rest of Luzon and the Visayas and Mindanao regions are expected to experience partly cloudy to clody skies with isolated rainshowers or thunderstorms.

PAGASA officially declared the start of the Habagat season on Friday, May 30.

Heat index

Despite the expected rains, several areas are forecast to have a “danger level” of heat index on Monday, with the highest 46 degrees Celsius expected to be measured by the synoptic station in ISU Echague, Isabela.

The following areas with weather stations are also expected to measure a "danger level" heat index:

• Calayan, Cagayan - 42 degrees 
• Aparri, Cagayan - 43 degrees
• Tuguegarao, Cagayan - 45 degrees
• Baler, Aurora - 43 degrees
• Casiguran, Aurora - 43 degrees
• Infanta, Quezon - 44 degrees
• Alabat, Quezon - 44 degrees
• Calapan, Oriental Mindoro - 42 degrees
• Coron, Palawan - 43 degrees
• San Jose, Occidental Mindoro - 42 degrees
• Cuyo, Palawan - 42 degrees
• Daet, Camarines Norte - 44 degrees
• Legazpi, Albay - 42 degrees
• Virac, Catanduanes - 42 degrees
• Masbate City, Masbate - 44 degrees
• Juban, Sorsogon - 43 degrees
• CBSUA-PB, Camarines Sur - 42 degrees
• Roxas City, Capiz - 43 degrees
• Mambusao, Capiz - 43 degrees
• Iloilo City, Iloilo - 42 degrees
• Dumangas, Iloilo - 42 degrees
• Siquijor, Siquijor - 42 degrees
• Catarman, Northern Samar - 43 degrees
• Catbalogan, Western Samar - 43 degrees
• Tacloban City, Leyte - 43 degrees
• Borongan, Eastern Samar - 43 degrees
• Guiuan, Eastern Samar - 42 degrees
• Maasin, Southern Leyte - 42 degrees
• Dipolog, Zamboanga Del Sur - 45 degrees
• Zamboanga City, Zamboanga Del Sur - 42 degrees
• Hinatuan, Surigao Del Sur - 42 degrees
• Butuan City, Agusan Del Norte - 42 degrees

The heat index is the measure of the temperature that a person feels in contrast to the actual air temperature. Computed by factoring in the humidity as well as the air temperature, the heat index measures "human discomfort" and is the "apparent temperature" felt by the human body.

PAGASA's heat index classification defines heat index temperatures ranging from 42°C to 51°C as being in the "danger" level, where "heat cramps and heat exhaustion are likely; heat stroke is probable with continued exposure."

The weather bureau urges the public to limit outdoor activities, remain hydrated, and wear fresh clothes to avoid heat-related illnesses. — Jon Viktor D. Cabuenas/BM, GMA Integrated News