According to ABS-CBN Resident Meteorologist Ariel Rojas, the phenomenon was caused by Rayleigh scattering.

Rayleigh scattering, where the colors of the visible light are dispersed differently, occurs when the sun is low on the horizon at sunrise or sunset, Rojas said.

The moisture from typhoon Pepito helped other suspended particles in dispersing the colors blue, indigo, violet, green in the atmosphere, leaving the shorter frequency yellow, orange and red to paint the sky.