The heat index or "init factor" may not be a measure of actual temperature, but it can make for very scorching days.
This was especially true this past week, as PAGASA noted heat indexes in the high forties at several monitoring stations across the country.
On Thursday, May 11, the heat index in Sangley Point, Cavite, hit 47.5°C.
In San Jose City, Occidental Mindoro, and Cabanatuan City, Nueva Ecija, the heat index was up to 48.1°C and 47.5°C, respectively, according to PAGASA data shared with GMA News' 24 Oras.
But Dagupan posted the highest heat index record to date this year, at a blistering 53.6°C last May 8. Dagupan also holds the distinction of having the highest heat index on record, at 55.8°C on May 6, 2016.
The heat index is an indication of apparent heat, based on actual temperature and humidity.
A heat index of just 41°C is already considered dangerous as it poses potential health risks.