MANILA, August 18, 2026 — The southwest monsoon, known locally as habagat, is bearing down on the Philippines this Tuesday, bringing heavy to intense rainfall across wide swaths of Luzon and Visayas and raising the threat of flash floods and landslides in vulnerable communities. A Low Pressure Area (LPA) hovering roughly 1,115 kilometers east of Northern Luzon is adding fuel to the monsoon's intensity. PAGASA issued its forecast at 4:00 AM today, valid until 4:00 AM on Wednesday, August 19, 2026.
What Is Driving Today's Weather?
The southwest monsoon — "habagat" in Filipino — is the seasonal wind system that sweeps moisture-laden air from the southwestern direction across the Philippines during the wet season, typically from June through September. When habagat is active, it can dump continuous, heavy rainfall particularly on the western and northern flanks of the country, saturating slopes and river basins and rapidly raising the risk of flooding and landslides.
Compounding conditions today, PAGASA tracked a Low Pressure Area (LPA) at 3:00 AM at approximately 19.6°N, 132.1°E — about 1,115 kilometers east of Northern Luzon. An LPA is a zone where atmospheric pressure is lower than its surroundings, drawing in surrounding air and moisture. While this LPA remains well offshore and is not yet a tropical cyclone, its presence is reinforcing the monsoon's strength and sustaining heavy rainfall over the western portions of the country. PAGASA will continue monitoring the LPA for any signs of development.
Region-by-Region Forecast
Northern and Western Luzon — Highest Risk Today
Residents of Benguet, La Union, Pangasinan, Ilocos Norte, Ilocos Sur, and the broader Cordillera Administrative Region (CAR) face the most serious weather today. PAGASA expects heavy to intense rainfall in these areas, caused directly by the southwest monsoon. The primary dangers are flash floods — especially in low-lying and riverside communities — and landslides in mountainous and hilly terrain. People living along riverbanks, in mountain valleys, or in areas historically prone to flooding and slope failures should be on heightened alert throughout the day.
Metro Manila and the Rest of Luzon
Metro Manila, the rest of the Ilocos Region, Central Luzon, CALABARZON, MIMAROPA, and other Luzon provinces not in the highest-risk category can expect cloudy skies with scattered rain showers and occasional thunderstorms, still driven by the southwest monsoon. While conditions are less intense than in the north, monsoon-driven downpours can still produce localized flooding in low-lying urban areas and flash floods in higher-elevation communities. Residents should be prepared for disruptions to the morning and evening commute.
Visayas
The southwest monsoon's reach extends into Western Visayas, where PAGASA forecasts cloudy skies with scattered rain showers and thunderstorms. Flash floods and landslides remain possible, particularly during and after heavy rain episodes. Eastern Visayas and the rest of the Visayas region will have partly cloudy to cloudy conditions, with isolated rain showers or thunderstorms possible. Residents across all Visayas provinces should remain weather-aware throughout Tuesday.
Mindanao
Most of Mindanao will experience partly cloudy to mostly cloudy skies with isolated to scattered rain showers and thunderstorms on Tuesday. PAGASA attributes these conditions to the southwest monsoon as well. Flash floods and landslides remain possible especially during severe thunderstorms. The eastern coastal sections of Mindanao face moderate to strong winds and rough to very rough seas, which pose additional hazards for maritime activities.
Decoding the Warnings: What Each Condition Means for You
PAGASA has not raised a tropical cyclone wind signal as of this bulletin — the LPA has not yet developed into a named storm. However, the active monsoon is producing conditions that carry real danger in specific areas. Understanding what each weather hazard means can help you make better decisions today. For a full guide, see how to read PAGASA's weather warnings.
Flash flood risk (Benguet, La Union, Pangasinan, Ilocos, Cordillera): This is not a distant possibility — PAGASA explicitly lists flash floods as an expected impact in these provinces. Flash floods can develop rapidly, within minutes to hours of heavy rainfall, and can sweep through narrow valleys and low-lying streets with little warning. Do not attempt to cross flooded roads or rivers on foot or by vehicle.
Landslide risk (Mountainous areas of Cordillera, Luzon highlands): Prolonged or intense rainfall saturates soil on slopes, reducing stability. Landslides can occur suddenly. Residents in hillside barangays or areas flagged by local government as landslide-prone should consider pre-emptive evacuation if conditions worsen.
Rough to very rough seas (Northern and western Luzon, eastern Mindanao): Coastal waters in these zones are dangerous for small vessels. Waves are forecast to be rough to very rough, conditions that can capsize small boats without warning.
What It Means for You
Commuters (Metro Manila and Urban Luzon)
Expect rain-related traffic slowdowns and possible street flooding in low-lying areas of Metro Manila and other urban centers across Luzon. Allow extra travel time for both the morning and evening commute. If your route passes through underpasses or flood-prone streets, have an alternate plan ready. Check your local government's flood alerts before heading out.
Fisherfolk and Small Boat Operators
PAGASA forecasts moderate to strong winds and rough to very rough coastal waters off the northern and western coasts of Luzon, and off the eastern coast of Mindanao. Small boat operators — including those on fishing bancas and outrigger vessels — are strongly advised to remain ashore today. Venturing into these waters carries a serious risk to life. Conditions in the rest of the country's coastal waters are moderate, but all mariners should verify local sea conditions before departure.
Farmers
Farmers in Ilocos, the Cordillera, and Pangasinan face the heaviest rainfall today. While monsoon rains replenish water sources, intense downpours can damage crops, erode topsoil, and flood lowland fields. Farmers in these areas should secure harvested produce and check drainage around their plots. Farmers in the Visayas and Mindanao should prepare for localized downpours that may temporarily disrupt fieldwork.
Students, Parents, and School Officials
Schools in Benguet, La Union, Pangasinan, Ilocos Norte, Ilocos Sur, and the Cordillera should closely monitor local government announcements regarding class suspensions, especially in areas at risk of flash floods and landslides. Parents should verify the status of classes before sending children to school, particularly in mountainous and riverside communities. Students who commute long distances should have contingency arrangements ready.
Outdoor Workers and Construction Sites
Workers on outdoor construction sites, in agriculture, and in other open-air industries across Luzon and Western Visayas face elevated risk today due to heavy rain, lightning from thunderstorms, and potential flooding. Site supervisors should assess conditions before the workday begins and be prepared to halt operations during heavy downpours or when lightning is in the vicinity.
Temperature and Humidity Outlook
PAGASA's 24-hour temperature and humidity readings recorded at the Science Garden weather station in Quezon City — covering the period ending at 6:00 PM yesterday — showed a maximum temperature of 27.8°C and a minimum of 24.8°C. Relative humidity reached a maximum of 96%, reflecting the highly moist atmospheric conditions that the active southwest monsoon brings. High humidity combined with warm temperatures can make heat feel more oppressive even on cloudy or rainy days, particularly in areas not receiving direct rainfall. Outdoor workers and vulnerable populations should stay hydrated.
Astronomical and Tidal Information
PAGASA's bulletin notes standard tidal and astronomical data for Tuesday, August 18, 2026. Sunrise and sunset times, as well as tidal patterns in major ports, should be factored in by maritime operators and coastal communities managing flood risk, particularly as high tides can worsen coastal flooding during heavy rain events.
PAGASA Bulletin Issued: 4:00 AM, August 18, 2026 | Valid Until: 4:00 AM, August 19, 2026 | LPA Position (3:00 AM): 19.6°N, 132.1°E — approximately 1,115 km east of Northern Luzon | Primary Weather System: Southwest Monsoon (Habagat)
Bottom Line
If you are in Benguet, La Union, Pangasinan, Ilocos Norte, Ilocos Sur, or the Cordillera region, treat today as a high-alert day: avoid flood-prone roads and riverbanks, stay away from hillsides that could be destabilized by rain, and follow all instructions from your local government unit. For everyone else across Luzon, Visayas, and Mindanao, be ready for rain showers and thunderstorms at any point in the day — carry rain gear, check for flood advisories in your area, and do not cross flooded roads under any circumstances.
Monitor official PAGASA updates at pagasa.dost.gov.ph