The National Capital Region (NCR) will experience up to a 45°C heat index on Thursday, April 25, according to PAGASA.
According to the state weather bureau's 5-day computed and 2-day forecast, Metro Manila, particularly Ninoy Aquino International Airport in Pasay City, Manila, will reach 45 degrees Celsius.
Meanwhile, the Science Garden in Quezon City will reach 43 degrees Celsius.
The 42°C to 51°C heat index is classified as "dangerous" by PAGASA, which means heat cramps, exhaustion, or heat stroke are likely to be experienced.
The Department of Health (DOH) earlier warned the public against heat-related illnesses that become more prevalent with extreme temperatures.
DOH thus advised drinking lots of water and staying in a place that has shade or is cooler.
Several local government units in the country including Metro Manila had already declared suspension of face-to-face classes on Thursday due to the extreme heat.