Indirect effects of typhoons contribute more to Habagat rains than direct impacts

A new study by researchers from Ateneo de Manila University, the Manila Observatory, PAGASA, and Japanese partner institutions reveals that indirect effects of tropical cyclones contribute more to heavy rainfall during the Southwest Monsoon (Habagat) season than direct impacts.

The team found after analyzing 62 years of weather data that indirect effects account for an average of 33.1% of rainfall, nearly twice as much as the 15.4% attributed to direct effects, with the remaining 51.5% caused by the southwest monsoon alone.

Examples include Typhoon Gaemi (Carina) in 2024 and 'enhanced Habagat' cases in 2012 and 2013, which brought significant rain despite no direct landfall.

In July 2024, Super Typhoon Carina, although it did not make landfall, strengthened the southwest monsoon, triggering torrential rains that claimed 48 lives and caused P8 billion in damage.

Researchers hope this distinction will improve weather forecasting and disaster preparedness as climate change increases the unpredictability of both tropical cyclones and seasonal rainfall.