Filipino researchers have found, through a groundbreaking new study spanning nearly two decades of data from 2006 to 2024, that the hottest days in the Philippines are more likely to produce hail.
The local study “Spatiotemporal Analysis of Hail Events in the Philippines” marks the first comprehensive analysis of hail occurrences in the country.
Its authors include Marco Polo Ibañez, John Manalo, and Generich Capuli of the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA), as well as Dr. Lyndon Mark Olaguera of the Ateneo de Manila University and the Manila Observatory.
These researchers discovered that hail events were most frequent during the dry-season months of March, April, and May—the period when surface temperatures peak and the atmosphere is primed for thunderstorms.
They also found that most hailstorms occurred during the hottest part of the day, between mid to late afternoon.
Luzon recorded the most hail events overall, while relatively larger hailstones were more observed in the Visayas and Mindanao.
The researchers attribute this to the weaker influence of the Southwest Monsoon in those regions, which allows localized convective storms to persist later into the year.
For the study, the researchers used a “multi-source, crowd-informed approach” relying on a wide range of sources aside from instrument data, including local government records, news media, and geotagged social media posts.
“Most people are surprised when hail happens because it is relatively rare in the Philippines,” Olaguera, senior author of the study, said.
“Many take photos or videos and share them online. Some are scared since it’s unusual, while others just treat it as a strange kind of rain. People usually explain it as part of strong thunderstorms, and some interpret hail as a warning or sign of climate change,” he added.
