NCR heat index hits scorching 43°C Thursday afternoon

As if things weren't hot enough as is, the nation's capital withered a scorching 43°C heat index on Thursday afternoon, April 14.

The heat index, also called the "init factor" or "real feel" is an indication of the apparent temperature based on a combination of the actual temperature and humidity.

While the heat index is not an indication of actual temperature, it is a useful tool for indicating the perceived temperature and for describing people's discomfort therefrom.

Actual normal body temperature is 37°C, and even just 38°C is already considered a high fever.

BA Racoma, lead developer of weather monitoring site ClimateX and an IT Officer of the DOST's Project NOAH, crunched the numbers and was surprised to find that the nation's capital was in the grips of a heat index already in the low 40's:

He noted that the actual temperature—which was already at a high 37.2°C as of 2 p.m., according to Project NOAH's automated sensor in Taguig—seemed that much worse due to the 42.7% relative humidity, resulting in a sweltering 43°C.

Meanwhile, forecasters at PAGASA's Science Garden outpost in Quezon City noted a high of 36.4°C as of 1:50 p.m.

"It's not the heat, it's also the humidity," Racoma told GMA News.

"While air temperature is a good baseline for measuring heat, we must also take into consideration how humid the air is in determining the perceived heat, hence the calculation of the heat index. Being a tropical country, besides having high air temperatures, the Philippines generally has high humidity. Kaya mainit," he concluded.

Racoma also prepared the following graph for GMA News Online, showing the actual temperature and "init factor" experienced in the NCR over the day:

He explained that the markers for "init" and "super init" in the graph were a bit of whimsy on his part, but are a useful rough guide to the level of discomfort that people may be experiencing. — GMA News