Tropical Depression Luis to Bring Heavy Rain Across Luzon Amid Southwest Monsoon

Tropical Depression Luis is expected to bring significant rainfall to many parts of Luzon over the next several days, the Philippine Atmospheric, Geophysical, and Astronomical Services Administration (PAGASA) reported on Sunday afternoon, August 2. As of 4 p.m., Luis was located 285 kilometers east of Baler, Aurora, moving northwest at 15 kilometers per hour with maximum sustained winds of 55 kilometers per hour and gusts reaching 70 kilometers per hour.

PAGASA indicated that Luis is likely to remain over the Philippine Sea but warned that a westward shift in its path could bring it near or even cause landfall in Northern or Central Luzon. The tropical depression may intensify into a tropical storm within hours but is forecast to weaken back to a tropical depression by Tuesday, August 4, and further degrade into a remnant low by Wednesday, August 5.

The weather bureau issued an updated rainfall advisory at 5 p.m. on Sunday, identifying areas expected to experience moderate to heavy rain ranging from 50 to 100 millimeters within the next 48 hours. From Sunday afternoon to Monday afternoon, these areas include Pangasinan, Cagayan, Isabela, Quirino, Zambales, Tarlac, Nueva Ecija, Bulacan, Aurora, and Quezon. From Monday afternoon to Tuesday afternoon, the advisory expanded to include La Union, Benguet, Pampanga, Bataan, Metro Manila, Cavite, Batangas, and Rizal, among others.

Beyond these specific provinces, Luis is also affecting the broader Ilocos Region, Cagayan Valley, Central Luzon, Calabarzon, Metro Manila, Bicol, the Cordillera Administrative Region, Occidental and Oriental Mindoro, Marinduque, Romblon, and Western Visayas. Scattered rain showers and thunderstorms are expected to continue across these areas on Sunday evening.

In addition to Luis, the southwest monsoon, locally known as habagat, will contribute to the rainfall this week. The monsoon is being enhanced by Typhoon Dolphin, which is currently outside the Philippine Area of Responsibility (PAR) but is expected to strengthen the habagat’s effects. PAGASA’s rainfall outlook for the southwest monsoon forecasts moderate to heavy rain of 50 to 100 millimeters over Occidental Mindoro from Monday afternoon to Tuesday afternoon. From Tuesday afternoon to Wednesday afternoon, heavier rainfall between 100 and 200 millimeters is expected in Zambales, Bataan, and Occidental Mindoro, with moderate to heavy rain continuing in other provinces including La Union, Pangasinan, Benguet, Tarlac, Pampanga, Bulacan, Metro Manila, Cavite, Rizal, Batangas, and Antique.

As of Sunday evening, fewer areas remained under Tropical Cyclone Wind Signal No. 1 due to Luis, as its strongest winds are expected to stay mostly offshore. These areas include the Polillo Islands, parts of Camarines Norte, northern Camarines Sur, and northern Catanduanes. PAGASA has not ruled out raising the signal to No. 2 should Luis intensify into a tropical storm.

The outer bands of Luis and the southwest monsoon are also generating strong to gale-force gusts in affected regions. Moderate to rough sea conditions are forecast in several coastal areas, prompting advisories for small vessels to take precautionary measures or avoid sailing if possible.

By Wednesday, Luis is expected to weaken into a remnant low and may be absorbed into the circulation of Typhoon Dolphin, which as of Sunday afternoon was located approximately 3,100 kilometers east of extreme Northern Luzon. Dolphin is moving west-northwest at 25 kilometers per hour with maximum sustained winds of 175 kilometers per hour and gusts up to 215 kilometers per hour. While PAGASA considers it less likely that Dolphin will enter the PAR, it will nonetheless enhance the southwest monsoon’s rainfall.

Luis marks the 12th tropical cyclone to affect the Philippines in 2026 and the first for August. PAGASA had previously forecasted that two to four tropical cyclones could develop within or enter the PAR during the month. Residents in affected areas are advised to monitor updates and prepare for possible flooding and other weather-related hazards as the situation evolves.