PAGASA Declares Rainy Season Onset on June 4 as Southwest Monsoon Begins on Normal Schedule

The Philippine Atmospheric, Geophysical, and Astronomical Services Administration declared the start of the rainy season on Thursday, June 4, 2026, five days after it announced the onset of the southwest monsoon or habagat. PAGASA said the southwest monsoon brought occasional to frequent rain over the past five days.

“This signifies the onset of the rainy season across the western sections of Luzon and the Visayas,” the agency stated.

Thirteen rainfall monitoring stations in the western portions of Luzon and the Visayas serve as the basis for the declaration. At least seven of the stations, or more than 50 percent, must record a total of at least 25 millimeters of rain in a five-day period, with at least 1 millimeter on each of three consecutive days.

Prevailing winds must also show westerly components over the western Philippines.

The rainy season typically begins in the second half of May or the first half of June and continues through October or November. PAGASA noted that monsoon breaks, periods of very little or no rainfall lasting several days or weeks, can still occur during the season.

PAGASA warned that a looming El Niño, which might begin in the June-July-August 2026 period, could trigger more rain from the southwest monsoon because the phenomenon disrupts wind patterns.

Tropical cyclones can also pull and enhance the southwest monsoon. From June to November 2026, PAGASA said nine to 13 tropical cyclones could form within or enter the Philippine Area of Responsibility. The Philippines has recorded four tropical cyclones so far in 2026, compared with an annual average of 20.

“The public and all concerned agencies are advised to take precautionary measures against the adverse impacts of the rainy season, habagat, and other climate and weather events,” PAGASA said.