37 areas hit 'danger level' heat index on May 21

Thirty-seven areas across the Philippines are expected to reach a 'danger level' heat index on Wednesday, May 21, according to PAGASA's forecast.

The highest heat index of 46°C is predicted for Dagupan City in Pangasinan and Aparri, Cagayan, while other cities like Laoag City and Tuguegarao City in Cagayan are expected to reach 45°C.

PAGASA defines the 'danger' level as temperatures ranging from 42°C to 51°C, where heat cramps and exhaustion are likely and heat stroke is probable with continued exposure.

The heat index measures human discomfort by factoring in both air temperature and humidity, providing an apparent temperature felt by the body.

PAGASA has advised the public to limit outdoor activities, stay hydrated, and wear fresh clothes to avoid heat-related illnesses.

The Department of Health recommends drinking up to 10 glasses of water daily for those with prolonged sun exposure as some areas may reach a dangerous 50°C.