The weather systems that affected the country during the month were the northeast monsoon, intertropical convergence zone (ITCZ), tail end of cold front, tropical depression “Zigzag” (December 25-28) which made landfall over Eastern Samar and ridge of high pressure area. (View Rainfall Charts)

Rainfall over northern Catanduanes, most parts of Eastern Visayan Region, eastern section of Bohol and CARAGA were greater than 500 mm. Quezon province, Camarines Norte, rest of Eastern Visayan Region, northern Cebu, western Bohol, Misamis Oriental and northern Davao recorded 301 to 500 mm of rainfall. Batanes, Cagayan, Aurora provinces, the rest of Bicol Region, northern Palawan, southern Cebu, Negros provinces and Central Mindanao had 101 to 300 mm while the rest of the country received below 100 mm of rainfall.

Significant rainfall events occurred over Southern Leyte and Northeastern Mindanao. Surigao weather station recorded 2nd highest 24-hour rainfall 556.4 mm last December 18, 2003 (the highest recorded 24–hour rainfall was last November 18, 1968 in the amount of 564.7 mm). Maasin weather station received 281.9 mm 24 hour rainfall on the same date breaking its record of 222.6 mm that occurred November 12, 1990. Five consecutive days rainfall recorded over Surigao and Maasin are 1,239.7 and 722.7 mm, respectively. Continuous rainfall was caused by a low pressure area embedded in the Intertropical Convergenze Zone. This extreme rainfall event was one of the factors that contributed to the landslides that occurred over Southern Leyte.

Cooler than normal air temperatures prevailed in many parts of the country. Average temperature ranges over the archipelago are as follows: mountainous areas in the Cordillera region, from 12°C to 22°C; northern Luzon which was exposed to the northeast wind flow, 16°C to 27°C; the mountainous areas of Mindanao, from 19°C to 28°C; and other parts of the country, from 22°C to 31°C. Lowest temperature for the month was observed in Baguio City at 9.2°C while the highest temperature of 34.8°C was recorded in Butuan for this month.

The continued northeast monsoon activity, intertropical convergence zone, tail end of cold front, ridge of high pressure area will likely influence the weather for the month. There is a low chance of tropical cyclone occurrence in the Philippine Area of Responsibility (PAR).

Most parts of the country will have less than 100 mm of rainfall while the eastern sections of Luzon and Central Visayas will have 101-300 mm. More than 500 mm is expected in Northeastern Mindanao.

Expected range of temperatures are as follows: 13°C to 23°C over Cordillera Region, 19°C to 31°C over Eastern Luzon, 20°C to 32°C over Western Luzon, 21°C to 32°C over Visayas, 19°C to 29°C over mountainous areas of Mindanao and 22°C to 32°C over the rest of Mindanao.