Cloudy skies with scattered rain showers and thunderstorms could affect Palawan, Visayas, and Mindanao in the next 24 hours, said the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) on Tuesday afternoon, May 18.

ITCZ is a region where trade winds from the northern and southern hemispheres converge and characterized by frequent and often severe thunderstorms.

Meanwhile, the easterlies will continue to bring hot and humid weather conditions across Metro Manila and the rest of the country.

PAGASA's monitoring on Tuesday showed that heat index values in 11 areas have reached "dangerous" levels due to the high likelihood of heat cramps and heat exhaustion.

Monitoring stations that recorded above 40 degrees Celsius heat index values on Tuesday are the following:

Aparri, Cagayan (46 degrees Celsius, 11 a.m.)

Laoag City, Ilocos Norte (46°C, 2 p.m.)

Catbalogan, Western Samar (45°C, 2 p.m.)

Clark Airport, Pampanga (44°C, 2 p.m.)

Zamboanga City, Zamboanga del Sur (44°C, 2 p.m.)

San Jose, Occidental Mindoro (43°C, 11 a.m.)

Coron, Palawan (42°C, 11 a.m.)

Iba, Zambales (42°C, 2 p.m.)

Sinait, Ilocos Sur (42°C, 11 a.m.)

Puerto Princesa City, Palawan (41°C, 11 a.m.)

Sangley Point, Cavite (41°C, 11 a.m.)

The heat index is the measurement of how hot it feels when relative humidity is factored in with the actual air temperature.

The highest heat index so far in 2021 was recorded in Dagupan City, Pangasinan on May 14 at 53℃.

PAGASA said that warm and humid weather conditions may persist until early afternoon, while possible sudden but short-lived rains from localized thunderstorms may occur from late afternoon until evening.

Severe thunderstorms are often associated with bursts of heavy rainfall, lightning, thunder, and gusty winds that usually last up to two hours.

It advised the public to take necessary precautionary measures in case flooding or landslides occur.