August, 2020, saw six tropical cyclones inside the Philippine area of responsibility (PAR) but not even one has hit land. According to a specialist at the Philippine Atmospheric, Geophysical, and Astronomical Services Administration (PAGASA), the developing La Niña may have influenced the cyclone formation and track within the PAR.

Ana Liza Solis, chief of the PAGASA's climate monitoring and prediction section, said that during the pre-development of a La Niña, the southwest monsoon or "habagat" activity is "weaker than average."

A pre-La Niña event is also manifested by strong easterlies or the warm and humid winds coming from the Pacific. 

These winds tend to push the cyclones northward away from the country, she added.

So far, 11 cyclones have entered the PAR this year. In August alone, six cyclones have formed within the PAR namely "Enteng," "Ferdie," "Gener," "Helen," "Igme," and "Julian." 

Based on the PAGASA's historical record, an average of two to four tropical cyclones enter or form inside the country's area of responsibility in August.

With six cyclones that formed in August, 2020, it now holds the second most number of named cyclones within the PAR in recorded history. This was tied with August, 2003, also with six cyclones.

Solis said the most number of named cyclones in history was documented in August, 1984, and August, 1978, with seven tropical cyclones each.

"Despite this, below average rainfall was recorded in Luzon, except in Mindanao where it received above normal rainfall due to the ITCZ (intertropical convergence zone)," she added.

She pointed out that the developing La Niña also has an effect on the number of developing cyclones near the country.

"The warmer than average SST (sea surface temperature) near the Philippine Sea or the West Pacific and cooler SSTs in the central and east Pacific, which we call see-saw pattern, can cause more tropical cyclone development in western north Pacific and then further north oscillation of the ITCZ (intertropical convergence zone)," Solis said.

"This could change in a couple of weeks due to short term intraseasonal variability," she added.

PAGASA last month said there is an increasing chance that La Niña will develop by the end of September or October. 

Solis said the looming La Niña may have a significant impact on the rainfall in Luzon by December, and Mindanao by January until February. 

Weather in the coming days

PAGASA said the southwest monsoon activity will remain weak and may not have a widespread impact over the country. 

Partly cloudy to cloudy skies, particularly in the morning, will prevail. There is a high chance of isolated afternoon or evening rain showers due to localized thunderstorms throughout the week.

Based on PAGASA's extended weather outlook until Sept. 11 (Friday), air temperature will range from 25 to 33 degrees Celsius in Metro Manila, 24 to 35 degrees Celsius in Tuguegarao City, 16 to 25 degrees Celsius in Baguio City, 25 to 33 degrees Celsius in Cebu City, and 26 to 33 degrees Celsius in Davao City.