Twenty-six areas in the Philippine registered a heat index of over 40 degrees Celsius, including the Ninoy Aquino International Airport in Pasay which it 42 degree Celsius, the Philippine Atmospheric Geophysical and Astronomical Services Administration (Pagasa) said Monday,

The readings were reported as of 5 pm. The Science Garden in Quezon City, which had heat index of below 40 degrees last week, crossed 40 degrees Celsius Monday.

On Tuesday, Ninoy Aquino International Airport is forecast to experience 42 degrees Celsius in terms of heat index.

Roxas City in Capiz and Zamboanga City had the highest reading of 45 degrees.

The heat index shows how hot it feels outside, taking into account humidity and temperature.

Meanwhile, the Department of Health is verifying if six deaths were due to heat-related illnesses.

The DOH said 34 cases of heat-related illnesses have been recorded this year, as of April 18.

It said most of the cases were from Central Visayas, Ilocos Region, and Soccsksargen. DMS