MANILA, April 29 (Reuters) – 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.