Phases of the El Niño Southern Oscillation (ENSO) known as the El Niño (warm phase) and the La Niña (cold phase), greatly influence Philippine climate variability. The continued cooling trend in the equatorial Pacific Ocean from March to June 2007 brought the sea surface temperature (SST) anomalies to its significantly below average value during July, indicating development of La Niña conditions. The cooling trend persisted through August and the weak La Niña event started September 2007. It reached its moderate strength during November and slightly intensified during December. Most ENSO forecast models indicate a moderate-to-strong La Niña through February 2008, followed by a gradual weakening thereafter. The probability of returning to neutral conditions becomes most likely during the second half of the year.


January to March

The period covers the second half of the Northeast (NE) monsoon season, locally known as “Amihan”. The peak of the La Niña episode is expected during this period and will probably enhance the northeast monsoon activity bringing rains over the eastern sections of the country. Flood and flash flood are likely to occur in affected areas. The weather systems that are likely to affect the country are the Northeast monsoon, tail-end of cold front, inter-tropical convergence zone (ITCZ), ridge of high pressure area, and the easterlies. Two (2) or three (3) tropical cyclones are expected to form or enter the Philippine Area of Responsibility (PAR) during the period. Weakening of the NE monsoon is expected during the later part of March that signals the coming of the North Pacific trades, bringing warm and humid weather to the country.

Rainfall conditions are likely to be above normal over a large portion of Luzon and Visayas, except Ilocos Norte, where below normal rainfall is expected. Mindanao will experience near normal to above normal rainfall condition. The rest of the country will likely experience near normal rainfall conditions.


April to June

Weakening of the La Niña episode and the probable shift towards neutral condition of the central and eastern equatorial Pacific are expected during this period. Likewise, the transition phase from the NE to the Southwest (SW) monsoon commonly known as “Habagat”, starts. This extends up to mid May where the onset of the rainy season is expected to follow. Normal start of the rains associated with the SW monsoon under Type I Climate is therefore likely to occur from mid May to the first half of June. Thunderstorms are expected which may produce incidences of excessive rains causing flood and landslides.

The weather systems that are usually associated with this period are the Intertropical Convergence Zone (ITCZ), easterlies, monsoon trough, SW monsoon, ridge of high-pressure system, and the passage of three (3) to five (5) tropical cyclones. The occurrence of tropical cyclone in May will likely trigger the onset of the rains. These cyclones are predicted to follow a normal track, usually across Luzon or Visayas area.

Near normal rainfall conditions may occur over most parts of the country. Camarines Norte, Palawan, western and central Visayas, Western Mindanao, and western sections of Maguindanao, Sultan Kudarat and South Cotabato, will likely experience above normal rainfall, with some patches of below normal over some areas of the country.


July to September

ENSO neutral condition is expected during this period. This is the peak of the SW monsoon “Habagat” season and tropical cyclone activity is likewise at its maximum. Thunderstorms, heavy rains and strong winds are the likely scenarios. The ITCZ runs over most of the Philippines during July and reaches its northernmost position during August. Eight (8) to ten (10) tropical cyclones are expected to develop/enter in the PAR with possible tracks located over Northern Luzon. The North Pacific High pressure system is also expected to affect the country during September when weakening of the SW monsoon is expected to start.

Rainfall condition during the period is likely to be near normal in most parts of the country. However portions of Zambales, National Capital Region (NCR), Cavite and southern Palawan are likely to experience below normal rainfall values.


October to December

The gradual shift of the season from SW (HABAGAT) to NE (AMIHAN), continues until October, followed by the recession of the SW monsoon rains. This covers the first half of the NE monsoon season and the expected weather systems to influence the country are the tail end of the cold front, northeast monsoon, intertropical convergence zone (ITCZ), ridge of high pressure area, easterlies and about three (3) to six (6) tropical cyclones. Tropical cyclones are likely to cross Luzon and Visayas and may also recurve to the northeast (NE) direction during the period.

Rainfall for the period is expected to be above normal to near normal in most areas of Luzon. Near normal rainfall is likely to occur over Eastern Visayas, and above normal over Central and Western Visayas including Western and Southern Mindanao .

The Climate Information, Monitoring and Prediction Center (CLIMPC) of PAGASA will continue to monitor the atmospheric and oceanic conditions affecting the country. Updates and advisories will be issued as appropriate..