MANILA, September 20, 2026 — Palawan residents face the most serious weather threat in the country today as the southwest monsoon — locally known as habagat — pushes into the western section of Southern Luzon, according to the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA). The agency's 4:00 AM bulletin, valid through 4:00 AM on Monday, September 21, warns of flash floods and landslides driven by moderate to at times heavy rains across the island province, while the rest of the Philippines contends with isolated showers and thunderstorms throughout the day.
What Is Driving Today's Weather
The primary weather engine today is the southwest monsoon, which PAGASA identifies as directly affecting the western section of Southern Luzon. The southwest monsoon — known in Filipino as habagat — is a seasonal wind system that blows moist air from the South China Sea and the West Philippine Sea into the country's western coast each year, typically from June through September. When it strengthens or surges, it funnels large amounts of moisture onto exposed western-facing landmasses like Palawan and Mindoro, producing sustained, often heavy rainfall rather than the quick, localized downpours that characterize ordinary afternoon showers.
Separately, localized thunderstorm activity is identified by PAGASA as the driver of isolated rainshowers across Metro Manila and the rest of the country — a reminder that even areas outside the monsoon's direct path are not entirely in the clear today.
Region-by-Region Forecast
Luzon
Palawan is under the heaviest weather today. PAGASA forecasts cloudy skies with scattered rains and thunderstorms for the entire province, with moderate to at times heavy rainfall raising the risk of flash floods and landslides. Residents in low-lying coastal communities and those living near hillsides or mountain slopes should be on alert throughout the day and into the night.
Occidental Mindoro and Oriental Mindoro are also under the southwest monsoon's influence, with partly cloudy to cloudy skies and isolated rainshowers or thunderstorms expected. Flash floods and landslides remain possible during severe thunderstorm episodes in these provinces.
Metro Manila can expect partly cloudy to cloudy skies with isolated rainshowers or thunderstorms, driven by localized thunderstorm development. While conditions are not as intense as Palawan, sudden downpours — particularly in the afternoon and evening — can still trigger flash floods in low-lying and flood-prone streets across the capital region. PAGASA notes the same flash flood and landslide hazard applies during any severe thunderstorm event.
The rest of Luzon — including Northern Luzon, Central Luzon, and other parts of Southern Luzon not specifically named — falls under the general forecast of partly cloudy to cloudy skies with isolated rainshowers or thunderstorms from localized sources.
Visayas
The Visayas region is included in PAGASA's broad forecast covering Metro Manila and "the rest of the country." Expect partly cloudy to cloudy skies with isolated rainshowers or thunderstorms across Eastern Visayas, Western Visayas, and Central Visayas. Flash floods and landslides remain a hazard wherever severe thunderstorms develop.
Mindanao
Mindanao likewise falls under the general nationwide forecast — partly cloudy to cloudy skies with isolated rainshowers or thunderstorms, with flash flood and landslide risks during severe thunderstorm activity. No distinct weather system is identified as targeting Mindanao specifically today, but the risk from localized convective storms remains real, particularly in mountainous provinces.
Wind and Coastal Water Conditions
Winds are light to moderate across all parts of the country today, but wave heights vary significantly by area and could create dangerous conditions for small vessels:
- Northern Luzon and the eastern sections of Central and Southern Luzon: Northeast to northwest winds; coastal waters are slight to moderate with wave heights of 1.2 to 2.1 meters.
- Mindanao: South to southwest winds; slight to moderate seas with wave heights of 0.6 to 1.8 meters.
- The rest of the country: Southwest to west winds; slight to moderate coastal waters with wave heights of 0.6 to 1.8 meters.
Wave heights of 1.2 to 2.1 meters along northern and eastern Luzon coastlines fall within a range that can capsize small motorized bancas and fishing vessels, particularly if conditions deteriorate during squalls associated with thunderstorms.
Decoding the Warnings: What These Hazards Mean for You
PAGASA does not list a color-coded rainfall warning or a tropical cyclone wind signal in today's bulletin. However, the agency explicitly flags the risk of flash floods and landslides for all areas in the forecast — a standard hazard statement that should be taken seriously, especially in areas receiving scattered or heavy rainfall like Palawan.
Flash floods can develop within minutes in low-lying streets, riverbeds, and drainage areas during intense downpours, while landslides are most likely on saturated slopes and in communities built near ravines or mountain ridges. If you are unsure how to read PAGASA's different warning types and what actions they require, how to read PAGASA's weather warnings is an essential reference before the rainy season deepens.
What It Means for You
Commuters
Metro Manila and other urban areas across the country should anticipate wet roads and reduced visibility during afternoon and evening thunderstorms. Allow extra travel time, avoid flooded underpasses and low-lying roads, and keep track of PAGASA updates before heading out. In Palawan, road travel in areas prone to flash floods or landslides should be carefully evaluated — consider postponing non-essential trips if heavy rain intensifies.
Fisherfolk and Small-Boat Operators
Wave heights of up to 2.1 meters along northern Luzon and eastern sections of Central and Southern Luzon pose a genuine risk to small vessels. PAGASA's forecast of light to moderate winds can shift quickly during thunderstorm events, raising seas without much warning. Small-boat operators in these areas are strongly advised to exercise caution and to avoid venturing far from shore today. Those in Mindanao and other parts of the country face somewhat lower wave heights of 0.6 to 1.8 meters, but the same caution applies.
Farmers
Farmers in Palawan should prepare for the possibility of sustained, moderate to heavy rainfall that could affect crops, irrigation systems, and farm access roads. Those in low-lying agricultural areas should check drainage systems and move harvested produce to dry storage. In the rest of the country, isolated thunderstorms may bring brief but intense downpours — monitor conditions closely before planning field work.
Students, Parents, and Schools
Parents and school administrators in Palawan should monitor local government announcements regarding class suspensions given the elevated rain and flash flood hazard today. Elsewhere, the isolated and intermittent nature of the showers means conditions are less likely to trigger suspensions — but students commuting during afternoon hours should be prepared for sudden downpours.
Outdoor Workers
Construction workers, delivery riders, market vendors, and others who work outdoors should plan for wet conditions throughout the day, particularly in the afternoon when localized thunderstorms are most likely to develop. Those in Palawan, Occidental Mindoro, and Oriental Mindoro face the highest exposure today and should have contingency plans if weather deteriorates significantly.
Temperature and Humidity Outlook
PAGASA's weather station at Science Garden in Diliman, Quezon City recorded a maximum temperature of 31.3°C at 11:00 AM yesterday and a minimum relative humidity of 24.2% at 6:00 AM yesterday — indicating warm morning air that was relatively dry before daytime heat and cloud buildup set in. Metro Manila residents can expect similarly warm conditions this morning, with cloud cover and afternoon showers potentially moderating the heat as the day progresses.
The moon is currently at 65% illumination, and Manila Bay tides today include a high of 1.04 meters at 3:15 AM and a low of 0.06 meters at 1:56 PM, according to tidal predictions provided by the National Mapping and Resource Information Authority (NAMRIA). Sunrise in Metro Manila is at 5:45 AM and sunset at 5:54 PM.
Bottom Line
If you are in Palawan, Occidental Mindoro, or Oriental Mindoro today — the single most important thing you can do is stay alert for flash floods and landslides, avoid areas near rivers and steep slopes during rain, and check your local government's emergency announcements throughout the day. For everyone else across the Philippines, be ready for isolated but potentially intense afternoon thunderstorms, keep travel flexible, and do not enter flooded roads regardless of how shallow the water appears.
Monitor official PAGASA updates at pagasa.dost.gov.ph.