QUEZON CITY, September 12, 2026 — Much of Luzon woke up Saturday under a wet and unsettled sky, as two weather systems work together to push scattered rains and thunderstorms across the country's most populous island. According to the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA), flash floods and landslides are possible in multiple regions today, and residents in vulnerable communities should be on alert throughout the day.
The agency issued its 24-hour public weather forecast at 4:00 AM on Saturday, September 12, 2026, valid until 4:00 AM on Sunday, September 13, 2026.
What Is Driving Today's Weather?
Two distinct weather systems are responsible for today's widespread rainfall, according to PAGASA.
The first is the trough of a low-pressure area (LPA) affecting the western section of Northern Luzon. A trough is simply an elongated zone of lower atmospheric pressure — think of it as the outer arm of a weather disturbance that pulls in moisture and squeezes it into rain. It does not need to be a full-blown storm to cause significant rainfall, and today it is doing exactly that over the north.
The second is the southwest monsoon, locally known as habagat. This is the seasonal wind pattern that blows moist air from the South China Sea and the Indian Ocean toward the Philippines between roughly June and October each year. When habagat is active, it funnels large amounts of moisture over the western side of the country, fueling persistent and sometimes heavy rain — especially when it interacts with land masses and mountain ranges that force the air upward, squeezing out even more precipitation.
Together, these two systems are producing a broad arc of wet weather that stretches from the northern tip of Luzon all the way down through Metro Manila and into Bicol.
Region-by-Region Forecast
Northern Luzon
PAGASA places the Ilocos Region, Cordillera Administrative Region (CAR), Isabela, Quirino, and Nueva Vizcaya under the direct influence of the LPA trough. These areas can expect cloudy skies with scattered rains and thunderstorms throughout the forecast period. The agency explicitly flags the risk of flash floods and landslides due to moderate to, at times, heavy rainfall. Mountainous areas in the Cordillera — including communities along steep slopes and riverbanks in provinces such as Benguet, Mountain Province, Ifugao, Kalinga, and Apayao — face the highest landslide exposure. Residents in low-lying riverside areas in Isabela, Quirino, and Nueva Vizcaya should watch for rapid rises in river levels.
Central and Southern Luzon, Metro Manila
The southwest monsoon keeps Metro Manila, Central Luzon, CALABARZON, MIMAROPA, and the Bicol Region under cloudy skies with scattered rains and thunderstorms on Saturday. Flash floods and landslides are likewise possible when moderate to heavy rains fall over these areas. Metro Manila commuters should anticipate wet roads and possible urban flooding in low-lying streets and underpasses. Residents of Bicol — particularly in provinces exposed to both the monsoon and mountain terrain, such as Camarines Sur and Albay — should stay informed about local flood advisories throughout the day.
Visayas
The Visayas region is in a comparatively calmer weather pattern on Saturday. PAGASA forecasts partly cloudy to cloudy skies with isolated rainshowers or thunderstorms for the Visayas, driven by localized thunderstorms rather than a large organized weather system. However, the agency reminds the public that even isolated thunderstorms can trigger flash floods or landslides where they strike hardest. Residents should not let the generally quieter forecast breed complacency — a single intense storm cell can still dump dangerous amounts of rain in a short time.
Mindanao
Like the Visayas, Mindanao falls under the "rest of the country" category in today's PAGASA forecast, with partly cloudy to cloudy skies and isolated rainshowers or thunderstorms expected from localized convective activity. The same caution applies: isolated does not mean harmless, and communities near rivers or on hilly terrain should stay alert to sudden changes in rainfall intensity.
Wind and Sea Conditions
Winds are light to moderate across the entire country on Saturday, but sea conditions vary by location, and fisherfolk should pay close attention to where they are headed.
- Extreme Northern Luzon faces the roughest waters today, with northeast to east winds and wave heights of 0.6 to 2.1 meters — classified as slight to moderate. The upper end of that range is significant for small boats and bancas.
- The rest of Luzon has southwest to southeast winds with wave heights of 0.6 to 1.5 meters — slight to moderate.
- Visayas and Mindanao see northwest to northeast winds with the calmest seas in today's forecast, at 0.6 to 1.2 meters — also classified as slight to moderate.
No gale warning is currently active, according to today's PAGASA bulletin. However, slight to moderate seas still carry risk for small and non-motorized watercraft, and conditions can deteriorate quickly near active thunderstorm cells.
Decoding the Hazard Warnings
PAGASA is not raising any tropical cyclone wind signal for September 12, 2026. There is no active storm. However, the agency's forecast does flag the risk of flash floods and landslides across Luzon — a hazard warning all Filipinos should take seriously even in the absence of a named typhoon.
Flash floods can develop within minutes when heavy or intense rain falls over an area faster than the ground can absorb it — particularly in urban zones with poor drainage, or in mountain valleys where water channels rapidly from higher elevations. Landslides, meanwhile, are triggered when saturated soil loses its grip on slopes. Both hazards can occur even from a single intense thunderstorm, not just from prolonged multi-day rainfall.
If your community sits along a riverbank, in a low-lying area, or on or below a steep hillside, today is not the day to wait and see — evacuate early if local authorities issue an advisory. Not sure how PAGASA's warning categories work? Read our explainer on how to read PAGASA's weather warnings for a full breakdown of rainfall color-coded alerts, storm signals, and heat index categories.
What Today's Weather Means for You
Commuters (Metro Manila and Luzon cities)
Expect wet, slow, and potentially flooded road conditions throughout the day, particularly if thunderstorms intensify in the mid-morning to afternoon hours — the typical peak period for convective rainfall. Allow extra travel time, avoid driving through flooded underpasses and streets where water depth is unknown, and keep an eye on local government social media pages for real-time flood updates.
Fisherfolk and Small-Boat Operators
Those operating off the northern tip of Luzon face the highest seas today, with waves potentially reaching 2.1 meters. Small bancas and non-motorized boats should remain in port in extreme Northern Luzon. Operators in the rest of Luzon, the Visayas, and Mindanao face lower but still meaningful wave heights. All fisherfolk are advised to check local coast guard advisories before heading out, and to return to port immediately if skies darken and thunder is heard.
Farmers
Farmers in Northern Luzon — particularly in the Ilocos and Cagayan Valley regions — should secure crops and farm equipment ahead of potentially heavy rains. In Cordillera, the combination of steep terrain and heavy rainfall raises the risk of soil erosion and damage to terraced fields. Farmers in Metro Manila's surrounding provinces under the southwest monsoon should similarly check irrigation channels and drainage to prevent waterlogging of crops.
Students and Parents
There is no class suspension indicated in today's PAGASA forecast, as the agency does not issue suspension orders — that authority rests with local government units. However, parents of children in schools located in flood-prone or landslide-prone areas of Northern and Central Luzon should monitor local LGU announcements throughout the morning. Keep emergency contact numbers ready and ensure children are not walking through flooded streets.
Outdoor Workers and Construction Sites
Workers on elevated structures, scaffolding, or outdoor construction sites in Luzon should exercise heightened caution today. Thunderstorms bring not only heavy rain but also lightning and strong gusty winds. Supervisors should have a clear protocol for suspending work and moving workers to safe shelter when thunderstorms approach. In the Visayas and Mindanao, the risk is lower but still present with isolated thunderstorms possible.
Temperature Outlook
PAGASA recorded a maximum temperature of 30.1°C at 12:00 PM yesterday at the Science Garden weather station in Diliman, Quezon City, with a minimum of 24.7°C at 6:00 AM. Relative humidity ranged from a high of 96 percent at 7:00 AM to a low of 62 percent at 12:00 PM. The high humidity reflects the moisture-laden air brought in by the southwest monsoon. No extreme heat index warning is indicated for today.
Tides and Astronomical Information for Metro Manila
For reference, NAMRIA's tidal predictions for Manila Bay on Saturday, September 12, 2026 are as follows: low tide of 0.36 meters at 3:28 AM, high tide of 1.16 meters at 10:46 AM, low tide of 0.28 meters at 5:36 PM, and high tide of 0.71 meters at 11:18 PM. Sunrise over Metro Manila is at 5:45 AM and sunset at 6:00 PM. The moon is at 2 percent illumination — essentially a new moon — rising at 6:28 AM and setting at 6:42 PM.
Bottom line: If you are in Luzon — especially in Northern Luzon's mountain provinces and Metro Manila's flood-prone barangays — the single most important thing you can do today is identify your nearest evacuation route and stay close to updates from your local government. Scattered to heavy rains and thunderstorms are forecast all day, and flash floods can develop quickly. Do not wait for floodwaters to rise before you act.
Monitor official PAGASA updates at pagasa.dost.gov.ph.