Metro Manila’s heat index, or human discomfort index, is expected to reach 39 degrees Celsius on Tuesday, according to the Philippine Atmospheric Geophysical and Astronomical Services Administration (PAGASA).

The highest heat index of 40.1 degrees Celsius is expected to happen in Tuguegarao City, PAGASA’s official website reported.

Check out the list below to see today’s forecast of the maximum temperature (HI_Tx) in other areas of the Philippines.

1. Baguio City

Heat Index maximum temperature (HI_Tx): 26.9 degrees Celsius

2. Cagayan De Oro City

Heat Index maximum temperature (HI_Tx): 35.9 degrees Celsius

3. Laoag City

Heat Index maximum temperature (HI_Tx): 38.8 degrees Celsius

4. Legaspi City

Heat Index maximum temperature (HI_Tx): 36.4 degrees Celsius

5. Iloilo/Bacolod City

Heat Index maximum temperature (HI_Tx): 38.9 degrees Celsius

6. Metro Cebu

Heat Index maximum temperature (HI_Tx): 38.5 degrees Celsius

7. Metro Davao

Heat Index maximum temperature (HI_Tx): 38.7 degrees Celsius

8. Puerto Princesa City

Heat Index maximum temperature (HI_Tx): 37.8 degrees Celsius

9. Subic Bay Metropolitan Authority (SBMA)

Heat Index maximum temperature (HI_Tx): 37.7 degrees Celsius

10. Tacloban City

Heat Index maximum temperature (HI_Tx): 35.6 degrees Celsius

11. Zamboanga City

Heat Index maximum temperature (HI_Tx): 37.8 degrees Celsius

The heat index forecast is valid from 5:00 am on Tuesday, April 19 to 5:00 am on Wednesday, April 20.

Again, PAGASA advises extreme caution for residents in areas with 32 to 41 degrees Celsius heat index because of possible heat exhaustion and heat cramps.

As for Baguio City, even if it's heat index maximum temperature is 26.9 degrees Celsius, residents are still advised to take caution because fatigue is still possible as well as heat cramps with prolonged exposure and continued activity under the sun.

Heat Index (air temperature + humidity) gives the "apparent" temperature, or what humans perceive as the temperature affecting their body. It is different from air temperature which is a measure of how hot or cold the air is.