The Philippine Atmospheric, Geophysical, and Astronomical Services Administration (PAGASA) declared the start of the rainy season on Thursday, June 4, 2026, five days after officially announcing the onset of the southwest monsoon, also known as habagat. This declaration is based on rainfall data from 13 monitoring stations in the western parts of Luzon and the Visayas, where at least seven stations recorded a total of 25 millimeters of rain over five consecutive days, with at least 1 mm on three of those days, and prevailing westerly winds. The rainy season typically runs from June to October or November, and PAGASA cautioned that a potential El Niño event starting in June-July-August 2026 could intensify rainfall from the southwest monsoon, while also forecasting nine to 13 tropical cyclones to form or enter the Philippine Area of Responsibility between June and November.