Filipinos may experience a “wet” Christmas this year due to the continued potential for La Niña development—a climate phenomenon known for its increased rainfall, according to an expert from the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA).

During its climate forum on Wednesday, Aug. 28, PAGASA Assistant Weather Services Chief Ana Liza Solis said climate model probabilities show the development of “borderline La Niña” or “La Niña-like conditions” in the next few months.

PAGASA’s latest forecast shows that most climate models, along with expert judgments, suggest a 66 percent chance of La Niña forming during the September-October-November 2024 season, with the likelihood of it persisting into the January-February-March 2025 season.

Solis said the probability of La Niña development, which has decreased from 70 percent, and the expected period, which has shifted from August-October to September-November, “clearly shows that there is a high level of uncertainty in the climate models.”

Despite the uncertainties, she said PAGASA still sees La Niña’s impact based on the rainfall forecasts for the next few months.

“Yung October-November-December-January, ‘yan ‘yung magiging critical na part na kung saan despite na borderline, weak, or La Niña-like conditions, andun yung impact na nakikita natin pagpasok ng amihan season (October through January will be a critical period, where, despite borderline, weak, or La Niña-like conditions, we will see the impact as we enter the amihan season),” she added.

Potential for heavy rainfall

Solis said that a wet Christmas is possible, with rain expected not only on Christmas Day but also potentially starting as early as October and extending into February.

“Based on past weather conditions, there may be occurrences of heavy rainfall events during the last quarter of the year—October through December—and possibly extending into January and February,” she added.

“The looming La Niña, La Niña-like conditions, or actual La Niña conditions could contribute to wetter conditions, in addition to the northeast monsoon or amihan season,” she explained.

Solis also pointed out that in the last quarter of the year, tropical cyclones are likely to make landfall and cross the country. 

The intertropical convergence zone (ITCZ), which serves as a breeding ground for potential tropical cyclones, will also be active during a La Niña.

Even if weather systems do not develop into tropical cyclones, they may still bring significant rainfall as low pressure areas, Solis said.

Is a super typhoon expected? 

“Kahit walang La Niña posible tayo makaranas ng mga malalakas na mga bagyo during amihan season kasi ito yung mas landfalling at crossing ang cyclones (Even without La Niña, we may still experience strong typhoons during the amihan season, which is known for more frequent landfalling and crossing cyclones),” Solis also said.

She reiterated that when La Niña is present, there is an increased likelihood of rain-bearing cyclones. 

La Niña usually triggers more rainfall than usual due to these cyclones and other rain-bearing weather systems, particularly during the amihan season, Solis said.

“Base sa historical data, kapag weak La Niña may mga instancces na marami tayong super typhoon category even kapag may weak La Niña kaya ingat pa rin (Historical data shows that even during weak La Niña events, there have been instances of super typhoons. Therefore, it is important to remain cautious),” she added.