It said the highest temperature record for this month and so far this year is 39.3∞C, recorded in Tuguegarao City, Cagayan last Monday.

The latest hottest temperature for Metro Manila was noted at 37∞C last Tuesday at the PAGASA Science Garden in Diliman, Quezon City.

Before, Metro Manila’s latest maximum temperature record was 36.8∞C last April 17.

The erstwhile maximum temperature record this year was 39∞C in General Santos City last April 14.

PAGASA supervising weather specialist Rosalina de Guzman said that the last time the same temperature was recorded in General Santos was April 15, 1988, adding that the warm weather in General Santos City during this time of the year is a "normal climate pattern" due to its geographical location near the equator.

The highest temperature record in Philippine history is 42.2∞C in Tuguegarao City on May 11, 1969.

PAGASA Climatology and Agrometeorology Branch (CAB) chief Dr. Flaviana Hilario said that despite the hot weather in the country at this time of the year, this year’s warm temperature is still lower compared to that in 2003, which registered the highest temperature in the country in the last five years as well as the lowest in terms of rainfall amount due to an El Niño phenomenon from 2002 to 2003.

She said the warm weather in the country is expected to reach its peak in the first half of May, the warmest month of the year before the onset of the rainy season in June.

Among the highest recorded temperature in the country was 38.6∞C at the Manila Port Area on May 17, 1915; 38.1∞C at the Ninoy Aquino International Airport (NAIA) on May 18, 1969; and 38.5∞C in Sangley Point, Cavite, on May 16, 1987.

PAGASA said that it is monitoring the possible onset of a La Niña phenomenon in the next three months.

The probability of a La Niña phenomenon development is now 50 percent, PAGASA said, based on numerical models of international meteorological bureaus, particularly those in the United States, Australia, and Japan.

La Niña is a weather phenomenon characterized by the extensive cooling of the equatorial Pacific and is associated with the occurrence of too much rainfall. This is in contrast to the El Niño phenomenon, which is associated with the unusual warming in the equatorial Pacific.

A La Niña phenomenon occurred last year and was followed by an El Niño phenomenon, which weakened last March.

Based on historic analogue, De Guzman said a La Niña may develop after the decay of an El Niño phenomenon, thus, a La Niña phenomenon is probable this year.

She, however, said that the sea surface temperature (SST), one of the benchmarks in determining a looming La Niña or El Niño phenomenon, is currently in neutral condition.

Aside from the La Niña phenomenon, the weather bureau is also preparing for the onset of the typhoon season beginning next month, as one tropical cyclone is expected to enter the Philippine Area of Responsibility (PAR) in May.

Ten to 13 tropical cyclones are expected to enter the PAR from May to September of this year.