There is a high chance the La Niña weather pattern will persist until the first quarter of 2022, said the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA).

PAGASA's Climate Monitoring and Prediction Section chief Ana Liza Solis said the prevalence of La Niña increases the likelihood of having above-normal rainfall conditions across most areas of the country.

"This means that it has a secondary impact such as flooding and landslides over vulnerable areas and sectors of the country," Solis said during the monthly climate outlook on Oct. 28.

PAGASA declared the onset of La Niña on Oct. 15

It is usually associated with above-normal rainfall conditions across most areas of the country during the last quarter of the year and the early months of the following year.

Based on the PAGASA's rainfall forecast, "generally near-to-above normal rainfall" is expected across the country from November to December 2021.

From January to March 2022, generally below-to-near normal rainfall conditions are likely in the Cordillera Administrative Region, Ilocos Region, and Central Luzon; generally near-to-above normal rainfall in Cagayan Valley, Metro Manila, and Southern Luzon; and generally above normal rainfall in Bicol, Visayas, and Mindanao.

Solis said the country may have two or three tropical cyclones in November and one or two cyclones in December.

She noted that cyclones occurring towards the end of the year are mostly "landfalling, crossing, and possibly disastrous" cyclones.

During the past La Niña events, she added that adverse impacts such as floods and landslides occurred during the northeast monsoon or "amihan" season.

The current La Niña occurs back-to-back with the just-concluded La Niña event in October 2020-June 2021.

Solis said that back-to-back La Niña episodes are not unusual, noting that the last six episodes occurred back-to-back.

These were in 2007-2008 and 2008-2009; 2010-2011 and 2011-2012; and 2016-2017 and 2017-2018.