At least six areas in the Philippines are expected to reach a dangerous level of heat index on Tuesday, April 9, according to the state weather bureau PAGASA.

In its Monday forecast, PAGASA said the following areas are projected to peak at a heat index of 42°C to 44°C:

• Dagupan City, Pangasinan
• Puerto Princesa City, Palawan
• Aborlan, Palawan
• Bacnotan, La Union
• Tuguegarao City, Cagayan
• Zamboanga City, Zamboanga del Sur

Heat index, according to PAGASA, is the human discomfort index that gives the "apparent" temperature, or what humans perceive or feel as the temperature affecting their body.

The effect-based danger classification ranges from 42°C to 51°C, and its effects on the body are that heat cramps and exhaustion are likely, and heat stroke is probable with continued exposure.