Scientists reveal the deadliest cyclones during Habagat never even hit land

Tropical cyclones forming far from the Philippines, which travel northeast without making landfall, have been found to cause more rainfall in Luzon and Visayas, challenging the belief that only landfalling cyclones are dangerous.

Researchers found that 15.4% of rainfall during the Habagat season comes from the direct effects of cyclones that hit the country, while 33.1% comes from distant cyclones. The remaining 51.5% is due to the monsoon alone.

These findings show that distant cyclones can deliver more than twice the rainfall of landfalling storms by pulling extra moisture over the land as it progresses.

Meanwhile, cyclones that form closer to the Philippines usually move west toward the West Philippine Sea or nearby land and interact less with the Habagat, resulting in weaker rainfall enhancement.

The Habagat, or southwest monsoon, which occurs from July to September, is often intensified by distant storms rather than by those that hit the country directly.

A striking example was Super Typhoon Carina in July 2024, which did not make landfall but dumped a month’s worth of rain in Quezon City within 24 hours. 

The said typhoon displaced over 6.3 million people and destroyed countless homes.

Scientists from Ateneo de Manila University, the Manila Observatory, the Philippine Atmospheric, Geophysical, and Astronomical Services Administration (PAGASA), and Japanese partner institutions have collaborated to analyze rainfall patterns along the country’s west coast

They examined 64 years of data (1961–2022) from July to September and found that in the four rainiest years—1962, 1972, 2012, and 2018—up to 41.5% of rainfall came from cyclones that never made landfall but boosted the monsoon.

This noted that these cyclones formed in the said years boosted the precipitation of the monsoon.

Scientists warn that distant cyclones can bring heavier rainfall and greater damage than storms that directly hit land.

As climate change makes weather patterns harder to predict, monitoring cyclone formation and its interaction with the monsoon is becoming crucial.

Now, Filipinos can better anticipate the risks of the Habagat season, especially when a cyclone is far from land.