QUEZON CITY, August 13, 2026 — The Southwest Monsoon is hammering large sections of Luzon on Thursday, bringing heavy to intense rainfall, flood threats, and rough coastal waters to millions of Filipinos. The state weather bureau PAGASA issued its 24-hour public weather forecast at 4:00 AM today, valid until 4:00 AM on August 14, 2026, painting a wet and hazardous picture for much of the country's northern island group while the rest of the Philippines braces for localized but still dangerous thunderstorms.
At the same time, Tropical Storm Nangka (2617) is tracked outside the Philippine Area of Responsibility (PAR), sitting approximately 260 kilometers east-northeast of extreme northern Luzon as of 3:00 AM today. While Nangka is not directly hitting Philippine soil, its presence is feeding moisture into the atmosphere and amplifying the Southwest Monsoon's reach and intensity over the country.
What Is Driving Today's Weather
The primary weather driver today is the Southwest Monsoon, known locally as habagat. The habagat is a seasonal wind system that blows from the southwest, drawing warm, moisture-laden air from the sea over the Philippine landmass, particularly over Luzon's western side. During the rainy season, the habagat is responsible for prolonged, heavy rainfall events — the kind that fill rivers, saturate hillsides, and overwhelm drainage systems in urban areas. When a tropical cyclone such as Nangka sits near the country even outside PAR, it can enhance and intensify the habagat's effects, pushing more rain-bearing winds toward Luzon's coasts and mountains.
Tropical Storm Nangka itself carries maximum sustained winds of 65 kilometers per hour near its center, with gustiness of up to 80 km/h. It is moving northeastward at 20 km/h, tracking away from the Philippine landmass. PAGASA has not placed any part of the Philippines under a tropical cyclone wind signal for Nangka at this time.
Region-by-Region Forecast
Luzon: The Hardest Hit
The heaviest weather impact today falls on Zambales and Bataan, which face heavy to intense rainfall under the full brunt of the Southwest Monsoon. Residents in these provinces should be on alert for potential flooding and landslides, particularly in low-lying areas near rivers and in communities near slopes and hillsides. PAGASA warns that flooding is a direct risk for these areas today.
The broader western and northern portions of Luzon — including Metro Manila, Ilocos Region, Cagayan Valley, CALABARZON, MIMAROPA, the Cordillera Administrative Region, Caraga, and Quezon province — can expect cloudy skies with scattered rains and thunderstorms caused by the same Southwest Monsoon. While rainfall in these areas may be less intense than in Zambales and Bataan, PAGASA cautions that the potential for flooding and landslides remains real due to the persistent nature of monsoon-driven rain.
The rest of Luzon will have cloudy skies with widely scattered to scattered rainshowers and thunderstorms. Severe thunderstorm episodes are possible and could trigger flash flooding in vulnerable communities.
Visayas: Partly Cloudy With Thunderstorm Risk
Most of the Visayas will see partly cloudy to cloudy skies with isolated rainshowers or thunderstorms today, driven by localized weather systems rather than the Southwest Monsoon. Conditions appear generally more manageable than in Luzon, but PAGASA notes that severe thunderstorms remain a possibility and could bring sudden, intense downpours capable of causing flash flooding in low-lying areas.
Mindanao: Isolated Showers and Thunderstorms
Mindanao will likewise experience partly cloudy to cloudy skies with isolated rainshowers or thunderstorms from localized weather systems. As in the Visayas, the risk of severe thunderstorms and the flash flooding they can produce should not be ignored, even though overall conditions are calmer than those in Luzon today.
Wind and Coastal Water Conditions
Strong to rough seas are a major concern today, especially in the north and west:
- Northern and western Luzon: Winds will be strong, coming from the southwest, with moderate to rough coastal waters and wave heights in the moderate to rough range. These are dangerous conditions for small watercraft.
- Rest of Luzon: Winds will be moderate from the southwest, with slight to moderate sea conditions.
- Visayas and Mindanao: Winds will be light to moderate in variable directions, with slight to moderate seas.
Decoding the Warnings
There are no active tropical cyclone wind signals over any part of the Philippines at this time, as Tropical Storm Nangka remains outside PAR. However, the threat of heavy rainfall, flooding, and landslides in Luzon constitutes a genuine safety concern that all residents in affected areas must take seriously. If you live in Zambales, Bataan, or any flood- or landslide-prone area in Luzon, do not wait for a formal signal before taking precautionary action — heavy monsoon rains can rapidly escalate.
For a full explanation of how PAGASA's warning systems work — from rainfall color codes to tropical cyclone wind signals — read our guide on how to read PAGASA's weather warnings. Understanding the thresholds can help you make faster, better decisions when conditions change quickly.
What It Means for You
Commuters — Especially in Luzon
If you are commuting in Metro Manila, Zambales, Bataan, or elsewhere across Luzon today, expect significant disruptions. Street flooding is a real possibility, particularly during peak monsoon downpours. Allow extra travel time, avoid underpasses and low-lying roads during heavy rain, and check your route before heading out. If you use public transport, expect delays and crowding as rain intensifies.
Fisherfolk and Small-Boat Operators
PAGASA's coastal water forecast is a direct warning for anyone planning to go out to sea today. The waters off northern and western Luzon are moderate to rough — conditions that are dangerous or potentially fatal for small boats and motorized bancas. Fisherfolk in these areas are strongly advised to remain ashore for the duration of today's forecast period. Those in the Visayas and Mindanao face lighter sea conditions but should still monitor updates, as isolated thunderstorms can rapidly produce dangerous waves and winds.
Farmers
Farmers across Luzon should secure crops, equipment, and livestock ahead of heavy monsoon rain. Flash flooding and strong winds during thunderstorms can damage standing crops and erode fields. Farmers in hilly areas of the Cordillera and Quezon province should watch for signs of landslides affecting farm access roads and irrigation channels.
Students, Parents, and School Administrators
Parents and school administrators in Zambales, Bataan, Metro Manila, and other Luzon provinces under heavy rain today should monitor local government announcements regarding class suspensions. Under PAGASA's rainfall warning system, local government units have the authority to suspend classes based on prevailing conditions. Do not send children to school if flooding is already occurring along usual routes.
Outdoor Workers
Construction workers, delivery personnel, and others who work outdoors in Luzon face elevated risks today from lightning associated with thunderstorms. When thunder is heard or lightning is seen, cease outdoor activities and seek sturdy shelter immediately. Do not take cover under trees or near metal structures.
Temperature Outlook
Based on PAGASA's recorded extremes at the PAGASA Weather Science Garden in Quezon City for the 24-hour period ending 9:00 PM yesterday, the minimum temperature recorded was 25.6°C at 5:00 AM, while relative humidity reached a minimum of 63% at 8:00 AM. These figures reflect the relatively cooler, more humid conditions that typically accompany active monsoon weather — a reminder that while it may not feel like a scorching heat day, the combination of rain, humidity, and occasional breaks of sun can still make conditions uncomfortable and physically taxing, especially for those working outdoors between downpours.
Bottom Line
If you are in Luzon today — especially Zambales, Bataan, and Metro Manila — prepare for heavy rain, possible flooding, and dangerous road conditions caused by the Southwest Monsoon. Stay off the sea in northern and western Luzon, monitor local government advisories for class suspensions, and avoid flood-prone areas. The single most important thing you can do right now is identify your safest exit route from your home or workplace should flooding begin.
Monitor official PAGASA updates at pagasa.dost.gov.ph.