HEAT BUSTER A woman crosses the Estrella-Pantaleon bridge in Makati City with an umbrella to protect her from the hot midday sun. INQUIRER file photo / MARIANNE BERMUDEZ

MANILA, Philippines — Seventeen areas across the country registered “dangerous” peak heat indices of or above 42ºC (degrees Celsius) on Thursday, said the Philippine Atmospheric, Geophysical, and Astronomical Services Administration (Pagasa).

Pagasa defines heat index as the “measure of the contribution that high humidity makes with abnormally high temperatures in reducing the body’s ability to cool itself.”

READ: Dangerous heat index forecast in 34 areas on Wednesday

A heat index ranging from 42ºC to 51ºC is considered part of the “danger category,” increasing the risk for various heat-related illnesses such as heat cramps, heat exhaustion, and even heat stroke during continued exposure increases.

Based on Pagasa’s latest computed heat index, Masbate City in Masbate and Dipolog, Zamboanga del Norte both registered the highest peak heat index at 45ºC.

In Metro Manila, Ninoy Aquino International Airport (Naia) in Pasay City logged a peak heat index of 42ºC.

Based on Pagasa’s latest computed heat index, the following areas registered a heat index of or above 42ºC:

• Masbate City, Masbate – 45ºC
• Maasin, Southern Leyte – 45ºC
• Virac (Synop), Catanduanes – 44ºC
• Tuguegarao City, Cagayan – 44ºC
• Catbalogan, Samar – 44ºC
• Bacnotan, La Union – 43ºC
• Laoag City, Ilocos Norte – 43ºC
• Aparri, Cagayan – 43ºC
• Roxas City, Capiz – 43ºC
• Catarman, Northern Samar – 43ºC
• Surigao City, Surigao del Norte – 43ºC
• Naia Pasay City, Metro Manila – 42ºC
• MMSU, Batac, Ilocos Norte – 42ºC
  ISU Echague, Isabela – 42ºC
• Baler (Radar), Aurora – 42ºC
• Tacloban City, Leyte – 42ºC
• Guiuan, Eastern Samar – 42ºC

This number is significantly lower compared to previous days when the number of areas  logging heat indices higher than 42ºC reached up to over 40.