Two phases, one crisis: Floods and drought under super El Niño

The Pacific Ocean determines whether conditions will be wet or dry, while the Indian Ocean influences the strength and timing of these extremes.

The Philippine rainfall crisis under the 2026-2027 super El Niño and Indian Ocean variability is expected to unfold in two phases: floods amid a negative Indian Ocean Dipole (IOD) from July to September 2026, followed by an abrupt transition to drought from October 2026 to May 2027.

The Philippines faces an unprecedented climate challenge as the 2026-2027 “Godzilla” super El Niño unfolds, described in the report as the strongest in at least a millennium.

Article continues after this advertisement

While the El Niño-Southern Oscillation (ENSO) has traditionally been viewed as the primary driver of rainfall variability, hydrological research cited in the report indicates that Philippine rainfall is shaped by the combined influences of ENSO, Indian Ocean Basin Wide (IOBW) warming and the Indian Ocean Dipole Mode (IODM).

FEATURED STORIES

NEWSINFO

NEWSINFO

NEWSINFO

Research by Dr. Glenn Tabios III of the University of the Philippines, based on data from 1980 to 2022, indicates that IOBW warming weakens the southwest monsoon, or Habagat, from June to August, while IODM exerts its strongest influence from September to November, a critical period for harvests and dam replenishment.

The negative IOD in mid-2026 buffered El Niño’s drying tendency, sustaining floods in Central Luzon and Thailand. Forecast models cited in the report, however, predict a shift to a strong positive IOD by October or November 2026, coinciding with El Niño’s peak.

The combination is projected to suppress rainfall, hasten the onset of drought and cause severe hydropower deficits.

Projected impacts cited in the report include a 40% to 60% reduction in rainfall in Luzon and the Visayas and a 60% to 80% deficiency in Mindanao, along with rice yield losses, food inflation and prolonged brownouts.

Article continues after this advertisement

By March to May 2027, heat indices of 52 to 55 degrees Celsius are projected, with thousands of heat-related deaths expected.

The report argues that the Philippines should not expect the IOD to moderate El Niño’s effects. Instead, resilience will require integrated forecasting using the Niño 3.4 and Dipole Mode Index, flexible water impounding systems, solar-powered irrigation and cooperative frameworks to help communities withstand an intensifying flood-to-drought cycle.

Article continues after this advertisement

Why the Pacific is not the only driver

The Philippines, an archipelago highly dependent on monsoon rainfall and seasonal climate cycles, is once again at the center of concerns over the effects of climate variability on agriculture, water security and energy systems.

While El Niño is often portrayed as the main driver of drought in the country, research led by Tabios indicates that rainfall variability is not controlled by the Pacific alone.

Instead, IOBW warming and IODM interact with ENSO to shape rainfall across the archipelago.

ENSO has traditionally been the dominant lens through which Philippine rainfall variability is understood.

Research by climate scientist Kevin Trenberth and his co-authors has shown that El Niño weakens the Walker circulation, suppresses convection and reduces rainfall, while La Niña enhances rainfall through stronger monsoon activity.

Tabios’ analysis of data from 1980 to 2022, however, indicates that ENSO alone cannot account for the full extent of rainfall variability.

His research also found that IOBW warming strengthens upper-level divergence, creating an anomalous anticyclone over the Western North Pacific and weakening the southwest monsoon.

IODM, meanwhile, primarily affects the September-to-November period, a critical transition season for rice harvesting and dam replenishment.

A 2020 study by Amirudin and other researchers found that a positive IOD, when coupled with El Niño, enhances subsidence over the Philippines and can lead to severe dryness.

The Food and Agriculture Organization (FAO) has reported that a negative IOD, by contrast, can temporarily buffer El Niño’s effects by sustaining moisture inflow from the eastern Indian Ocean.

In simple terms, the Pacific determines whether conditions will be wet or dry, while the Indian Ocean influences the strength and timing of those extremes.

A super El Niño in a global context

The report places the Niño 3.4 anomaly at plus 3 degrees Celsius in mid-September 2026, surpassing the benchmarks of the 1997-1998 and 2015-2016 El Niño events.

It cites the National Oceanic and Atmospheric Administration (NOAA) as estimating a 75% chance that the event will exceed all El Niño episodes since 1950 and a 90% probability that it will persist until May 2027.

The report also cites the World Meteorological Organization (WMO) as describing the event as “being supersized before our eyes.”

Climate Impact Lab projects 451,000 excess heat-related deaths globally between June 2026 and February 2027, including 6,500 in the Philippines and nearly 20,000 across Southeast Asia.

These projected deaths underscore the human consequences of climate variability beyond its agricultural and hydrological effects.

Phase 1: Floods amid a negative IOD

The Indian Ocean Dipole is defined by differences in sea surface temperatures between the western and eastern Indian Ocean.

A negative IOD occurs when the eastern Indian Ocean near Sumatra and Java is warmer than average, enhancing convection and moisture transport into Southeast Asia.

This inflow counteracts El Niño’s suppression of rainfall, producing above-normal precipitation in the Philippines and neighboring countries.

Tabios’ framework describes this as a “canceling phase,” in which Indian Ocean dynamics temporarily neutralize Pacific-driven drought signals.

PAGASA reported that Metro Manila and western Luzon received 305 millimeters of rain from Aug. 28 to 30, 2026, as the southwest monsoon was enhanced by a low-pressure area.

READ: Why Central Luzon and Metro Manila are sinking into deeper flood risk

Ipo and La Mesa dams exceeded spilling levels, triggering widespread flooding and landslides in Pampanga, Rizal and Metro Manila, according to the report.

In Thailand, more than 50 districts were submerged, with the heavy rains linked in the report to the same negative IOD moisture inflows that sustained the Philippine Habagat rains.

The 2020 study by Amirudin and other researchers found that interactions between the IOD and ENSO influence rainfall variability across Southeast Asia.

When El Niño coincides with a negative IOD, rainfall anomalies shift, producing wetter conditions in the eastern Indian Ocean and Maritime Continent.

This helps explain why Luzon and Thailand experienced flooding rather than drought despite El Niño’s strengthening in mid-2026.

Why the Habagat brought so much rain

The southwest monsoon carries large amounts of rainfall because it is a large-scale wind system driven by the seasonal heating contrast between land and ocean.

From June to September, the Asian continent heats faster than the surrounding seas, creating a low-pressure zone over South Asia. Moist air from the equatorial Indian Ocean and the West Philippine Sea is then drawn northward.

As this moisture-laden air rises over the rugged terrain of Luzon and the Visayas, it condenses and produces heavy rainfall.

The monsoon’s strength is amplified when sea surface temperatures in the Indian Ocean are high because warmer waters increase evaporation rates and atmospheric moisture content.

Research by Trenberth and his co-authors, citing the Clausius-Clapeyron relation, found that each 1-degree Celsius increase in sea surface temperature allows the atmosphere to hold about 7% more water vapor, contributing to heavier rainfall events.

In August and September 2026, this mechanism was intensified by a negative IOD. The eastern Indian Ocean near Sumatra was anomalously warm, feeding additional moisture into the monsoon circulation.

This influx counteracted El Niño’s drying tendency, sustaining the Habagat and producing destructive floods in Pampanga, Metro Manila and Thailand.

The study by Amirudin and other researchers found that negative IOD phases enhance rainfall in the Maritime Continent and Southeast Asia.

Thus, while the Pacific signaled drought, the Indian Ocean sustained rainfall, illustrating the complexity of climate teleconnections.

The 2026 floods underscore the need for multi-ocean seasonal forecasting that integrates the Niño 3.4 index, which measures Pacific ENSO strength, and the Dipole Mode Index, which measures Indian Ocean variability.

Without this dual perspective, forecasts risk misrepresenting rainfall outcomes and leaving communities unprepared for sudden swings between flood and drought.

Flooding damaged rice fields in Central Luzon, delaying harvests and causing waterlogging losses. Roads and bridges were destroyed, requiring emergency repairs, while dams exceeded safe levels and spillovers worsened downstream flooding.

The National Disaster Risk Reduction and Management Council estimated infrastructure damage at P6.3 billion and agricultural losses at P2.2 billion by early September 2026.

Phase 2: An abrupt shift to drought

Tabios has attributed regional differences in climate impacts across the Philippines to the country’s archipelagic geography, rugged terrain and exposure to both the Pacific and Indian oceans.

First, the archipelagic nature of the Philippines means its islands are surrounded by contrasting oceanic influences.

The eastern seaboard directly faces the Pacific, making it highly sensitive to ENSO-driven subsidence and weakened convection during El Niño years.

The western seaboard, meanwhile, interacts with the South China Sea and receives moisture inflows modulated by the Indian Ocean.

This dual exposure explains why Luzon and the Visayas often experience harsher droughts under El Niño, while southern Mindanao may still receive localized rainfall from Indian Ocean moisture transport.

Second, rugged and mountainous terrain enhances orographic rainfall.

Moist air masses carried by the southwest monsoon rise over mountain ranges such as the Sierra Madre, Cordillera and Mindanao highlands, producing heavy rainfall on windward slopes while leaving leeward areas drier.

During negative IOD phases, this orographic effect magnifies floods in Luzon and the Visayas. When the IOD turns positive, however, subsidence suppresses convection even in these rain-rich areas, leading to an abrupt shift toward drought.

Third, regional differences are reinforced by typhoon tracks.

Bicol and Eastern Visayas remain vulnerable to typhoons even during El Niño, creating alternating periods of flooding and drought.

Tabios’ research found that Central Luzon’s dependence on large reservoirs such as Angat, Pantabangan and Magat leaves the region highly exposed to ENSO-driven declines in inflows.

The FAO has reported that Mindanao, though buffered by the Intertropical Convergence Zone, can suffer localized droughts affecting corn, pineapple, banana and cacao production, with the effects compounded by the region’s reliance on hydropower.

The transition from floods from July to September 2026 to drought from October 2026 to May 2027 will therefore not be uniform across the country.

It reflects the interaction of archipelagic geography, mountainous terrain and dual-ocean teleconnections.

Island provinces experience dual-ocean variability, with alternating extremes disrupting agriculture and fisheries.

This complexity underscores the need for region-specific adaptation strategies — buffer stock systems in Luzon, diversified cropping in the Visayas and emergency feed programs in Mindanao — rather than a one-size-fits-all national plan.

How impacts will differ across regions

The regional differentiation of climate impacts shows how geography — whether an area is Pacific-facing or Indian Ocean-facing — and terrain interact with ENSO, IOD and orographic rainfall.

Table 1. Regional differentiation of climate impacts during the 2026-2027 flood-to-drought transition

Region type	Geographic exposure	Terrain influence	Climate-driver sensitivity	Expected impacts, October 2026-May 2027
Pacific-facing areas: Eastern Luzon, Bicol, Eastern Visayas and Caraga	Directly exposed to Pacific ENSO signals	Orographic uplift along the Sierra Madre, Bicol ranges and Mindanao highlands enhances rainfall during storms	Highly ENSO-dominated; drought intensifies when Niño 3.4 anomalies peak	Alternating floods from typhoon tracks and drought; erratic rainfall; crop stress in rice and coconut
Indian Ocean-facing areas: Western Luzon, Palawan, Western Visayas and Zamboanga	Influenced by the South China Sea and Indian Ocean moisture inflows	Lower mountain barriers and flatter terrain, with less orographic enhancement	Strongly modulated by IOD phases; a negative IOD sustains Habagat, while a positive IOD suppresses rainfall	Floods in September 2026, followed by sharp drought from November 2026 to May 2027; rice yield losses and reservoir deficits
Highland regions: Cordillera, Bukidnon and Compostela Valley	Moisture-laden winds are forced upward, producing localized heavy rainfall	Orographic rainfall dominates; leeward valleys remain dry	Sensitive to monsoon strength and buffered slightly by elevation	Localized floods during a negative IOD, followed by severe drought when subsidence dominates; corn and vegetable losses
Lowland plains: Central Luzon, Cagayan Valley, Cotabato and Davao lowlands	Dependent on reservoir-fed irrigation and river inflows	Flat terrain with limited natural water storage	ENSO-driven decline in inflows; reservoirs fail to replenish	Harsh droughts; deficits at Angat, Magat and Pulangi; hydropower shortages; increased rice imports
Island provinces: Palawan, Mindoro, Samar and Leyte	Surrounded by dual-ocean influences, with highly variable rainfall	Mixed terrain and coastal exposure	Sensitive to both ENSO and IOD; typhoon tracks add variability	Alternating floods and drought; disruption to fisheries; coastal flooding followed by water scarcity

Pacific-facing regions are most exposed to ENSO-driven drought as subsidence suppresses convection.

Indian Ocean-facing regions are more sensitive to IOD phases, experiencing floods during a negative IOD and drought during a positive IOD.

Highland areas amplify rainfall through orographic uplift but remain vulnerable to subsidence-driven drought.

Lowland areas are critically dependent on reservoirs, making them highly exposed to ENSO-induced declines in inflows.

Where the risks will be greatest

The severity of the projected impacts will vary across Philippine regions.

Northern and Central Luzon: Highly ENSO-dominated, these areas are projected to experience the harshest droughts because of weakened monsoon inflows and their reliance on large reservoirs.

Southern Luzon and Bicol: Alternating floods and droughts are expected as typhoons continue to cross Bicol even under El Niño, producing erratic rainfall.

Visayas: The region is vulnerable because of limited irrigation and its dependence on sugarcane and rice, both drought-sensitive crops. Hydropower shortages could exacerbate energy insecurity.

Mindanao: Localized droughts are expected to affect corn, pineapple, banana and cacao. Reliance on hydropower makes the region particularly exposed to water deficits.

These differences underscore the need for region-specific adaptation strategies rather than a one-size-fits-all approach.

What adaptation will require

According to Tabios, the Philippines should not expect the IOD to “save” the country from El Niño’s effects.

Instead, resilience requires several proactive measures.

Seasonal forecasting should integrate the Niño 3.4 and Dipole Mode Index to better anticipate transitions from flooding to drought.

Water infrastructure should also become more flexible, with small water impounding systems capable of storing floodwater for use during drought rather than relying solely on large dams vulnerable to extreme flooding.

Expanding solar-powered irrigation could reduce agriculture’s dependence on rainfall, while localized machinery and cooperative systems could give farmers greater access to tools and reduce their reliance on middleman-dominated value chains.

Energy sources should likewise be diversified by expanding solar and wind capacity to help buffer hydropower deficits during drought.

Preparing for a two-phase disaster

The 2026-2027 super El Niño, amplified by Indian Ocean variability and background global warming, represents a two-phase disaster in the report’s assessment: floods in mid-2026 followed by extreme drought through mid-2027.

Tabios’ framework indicates that Philippine rainfall variability is shaped by the interplay of ENSO, IOBW and IODM, with the Indian Ocean influencing the timing and severity of extremes.

For the Philippines, the report argues, resilience lies not in hoping that the IOD will moderate El Niño but in building adaptive infrastructure, improving forecasting and strengthening communities’ capacity to withstand increasing climate volatility.

The projected flood-to-drought transition also underscores the need for region-specific responses: buffer stock systems in Luzon, diversified cropping in the Visayas and emergency feed programs in Mindanao, rather than a single national approach. /dm

Your subscription could not be saved. Please try again.

Your subscription has been successful.

(Teodoro C. Mendoza is a retired professor and scientist of the Institute of Crop Science, College of Agriculture and Food Sciences, UP Los Baños, Laguna)