MANILA: The Philippines has cancelled in-person public school classes for the next two days and said the power grid on its main island could be strained as the country grapples with a heatwave that is also affecting other parts of Southeast Asia.

The state weather agency on Monday forecast temperatures in the capital region could reach 37 degrees Celsius (98.6 degrees Fahrenheit) in the next three days.

The agency said the heat index -- the actual temperature felt by the body to include relative humidity -- is expected to remain at a record 45 degrees Celsius (113° Fahrenheit), in the range which it classes as "dangerous" as conditions can trigger heat stroke from prolonged exposure.

The heat index could continue hitting record highs until the second week of May, Glaiza Escullar, a state weather forecaster, told DZBB radio station.

The heatwave is putting pressure on power supplies on the main island of Luzon, which accounts for three-quarters of economic output, with reserves thinning after 13 power plants had shut down earlier this month, the Philippines' grid operator said in a statement.

In Indonesia, warmer temperatures have been cited as a factor in a surge in cases of dengue fever, a mosquito-borne infection, to 35,000 cases last month from 15,000 a year earlier.

The El Nino weather pattern has prolonged the dry season and hotter temperatures have accelerated the mosquito lifecycle, Indonesian health ministry spokesperson Siti Nadia Tarmizi told state media Antara news agency.


DIZZINESS AND FAINTING

The Philippines' education ministry on Sunday had ordered public schools to shift to online learning due to the record heat index forecast, as classrooms can be crowded and most do not have air-conditioning.

Benjo Basas, chairperson of Teachers' Dignity Coalition, a group of educators, said the extreme heat is already taking a toll on teachers and students.

"We already have reports of high blood pressure and dizziness, and fainting for pupils and teachers in the past days," Basas told DWPM radio station.

Several private schools and universities not covered by the education ministry mandate have also shifted to online classes. Over 3.6 million public school students were already affected from similar suspensions of schooling last week.

Passengers at Manila's main airport are also struggling with temperatures inside the Terminal 3 building after two of its six cooling towers stopped working on Sunday.

Evaporative fans were being used to improve circulation and offer respite to passengers, the airport authority said on Monday.