Colombia and Venezuela Face a Hydropower Squeeze as El Niño Consolidates

Colombia's meteorological institute IDEAM has issued one of its most pointed warnings in years: the probability of El Niño consolidating in the second half of 2026 exceeds 90%, with 82% odds of a strong or very strong event from June onward, effects running into early 2027 — and the potential, IDEAM flags, for this to rank among the strongest events since 1950. That language tracks NOAA's July diagnostic, which gives a 97% chance of persistence into early spring 2027 and an 81% chance of very strong magnitude (Niño 3.4 ≥ +2.0 °C) in October–December 2026.

For Colombia and Venezuela, the exposure is concentrated in one place: the dams.

The mechanism: subsidence over the Andes

During El Niño, the rearranged Walker circulation places anomalous subsidence over northern South America. Convection is suppressed over the Colombian Andes and the Orinoco and Caribbean basins — precisely the catchments that feed the reservoirs supplying roughly 80% of Colombia's electricity. Reduced precipitation is also the canonical El Niño signal for Venezuela and Guyana, bringing drought stress, pressure on Venezuela's Guri dam complex, and — historically — elevated malaria transmission. The chain from Pacific sea-surface temperatures to Andean rainfall is a textbook case of the science of teleconnections.

Colombia's numbers: comfortable now, exposed later

The present position looks manageable. The National Interconnected System's aggregate reservoir level stood at 73.7% on 17 June 2026. But grid operator XM's scenario work is the reason for the alarm: under a very strong El Niño through the 2026–27 dry summer, reservoirs could fall to 19.3%. No rationing has been announced, and none may prove necessary — that is a scenario, not a forecast. The gap between 73.7% and 19.3%, however, is a measure of how much hydrology a very strong event can remove, and the memory of past rationing episodes is why utilities and regulators are moving early.

Water authorities are already pre-positioning. The CAR, the environmental authority for Cundinamarca — the department surrounding Bogotá — announced on 21 July 2026 that it had stored 300,000 cubic metres of water across 25 municipal water banks as a drought buffer. Expect more of this: the cheap interventions all sit on this side of the dry season.

Venezuela: thinner margins, less visibility

Venezuela shares the same climatological signal — reduced rainfall, drought, hydropower stress centred on the Guri dam, which anchors the national grid — but with far thinner institutional and financial margins. Tellingly, Venezuela is among the Latin American countries included in the FAO–WFP Joint Anticipatory Action Appeal covering June 2026 to March 2027, which seeks US$202 million to protect 8.8 million people across 22 high-risk countries; six of those are in Latin America and the Caribbean, Haiti among them. The appeal's premise is blunt economics: every $1 spent on anticipatory action prevents up to $7 in losses.

The regional health dimension deserves note. PAHO's analysis of 7 July 2026 lists cholera and other waterborne diseases, malaria, dengue, Zika and chikungunya among the diseases of concern for the Americas during this event, alongside heat stress, wildfire-smoke respiratory conditions and mental health impacts; 756 emergency hospitals were assessed for vulnerability to coastal flooding and supply-chain disruption. Drought-era outbreaks — malaria surges in Venezuela historically among them — are part of the El Niño pattern here.

Historical calibration

Colombia's grid survived the 2015–16 and 2023–24 events without collapse, but both left scars — price spikes, water-saving campaigns, near-miss rationing debates. Regionally, the 2023–24 Amazon drought disrupted hydropower across six countries, and Ecuador — facing the same Amazon-side drying — was forced to import Colombian power to avoid blackouts, a cushion that shrinks if Colombia's own reservoirs are stressed at the same time. That interdependence is the quiet risk of a synchronised regional drought; Ecuador's version of the problem is covered in our piece on Peru and Ecuador.

What to watch and when

The oceanic peak is forecast for November 2026–January 2027, but the hydrological crunch lags it: Colombia's dry season runs through the 2026–27 austral summer, and reservoir trajectories from December onward will determine whether XM's downside scenario stays hypothetical. Watch the SIN aggregate level against the 73.7% June baseline, XM's monthly scenario updates, any move from voluntary savings campaigns toward rationing, thermal-generation dispatch (the gas and coal backstop), and the electricity trade balance with Ecuador. For Venezuela, Guri levels and the pace of anticipatory-action funding are the indicators. IDEAM's warning horizon — effects into early 2027, including forest-fire risk — sets the calendar: the decisions that matter will be made before the rains fail, or don't.