El Niño and Renewable Energy: Solar, Wind and Hydropower Variability
Published: July 26, 2026 · 9 min read
TL;DR — Renewables Are Weather-Dependent, and El Niño Changes the Weather Everywhere at Once
El Niño reshuffles every renewable energy source simultaneously. Solar irradiation drops 10-20% in cloudier equatorial regions. Wind speeds shift 5-15% as jet streams reposition. Hydropower — still the world's largest renewable source — takes the biggest hit, with Brazil's reservoirs falling to 60-65% of capacity during the 2015-16 event and thermal backup generation costing $2.5 billion. As the 2026-2027 El Niño approaches, renewable-heavy grids in Brazil, Colombia, and Southern Africa face the highest exposure. Grid operators who incorporate ENSO forecasts into seasonal planning avoid the worst price spikes; those who do not end up firing expensive fossil fuel backup.
Solar Power: The Cloud Cover Problem
Solar power looks simple — panels convert photons to electrons — but its sensitivity to El Niño is real and regionally specific. During El Niño, warming of the central and eastern Pacific shifts atmospheric convection. Rising air over warm water produces deep convective clouds that spread across the tropics, and subtropical high-pressure systems that normally suppress cloud formation weaken. The net result is increased cloud cover over broad equatorial and subtropical zones — and cloud cover is the single largest variable controlling solar farm output.
Southeast Asia provides the clearest data. The region has added over 100 GW of solar since 2020, led by Vietnam (roughly 18 GW), Thailand (5 GW), and the Philippines (4 GW). World Bank Global Solar Atlas data shows El Niño months typically see global horizontal irradiance (GHI) reductions of 10-20% in the region, concentrated in pre-monsoon and monsoon-transition periods. For a 100 MW utility-scale solar farm at $0.05/kWh, a 15% output reduction over three months means roughly $540,000 in lost revenue. Rooftop PV owners see the same percentage reduction.
South America's solar belt — northern Chile, Peru, and northwest Argentina — normally sits under the descending branch of the Hadley circulation, where subsidence suppresses cloud formation. During El Niño, this weakens. The Atacama Desert, hosting some of the world's highest-yield solar farms including the 246 MW El Romero plant, sees a dip in direct normal irradiance (DNI) most pronounced in the austral summer. Chile's grid operator reported utility-scale solar generation 8-12% below forecast during the 2023-24 El Niño summer. Conversely, eastern Australia — which El Niño makes drier and clearer — sees rooftop PV output running 5-8% above seasonal averages, partially offsetting higher air-conditioning loads.
Wind Power: The Jet Stream Shuffle
Wind power output is governed by the position and strength of the polar and subtropical jet streams, both of which El Niño reshapes. The effects vary by hemisphere and region, but they are consistent enough across multiple El Niño events that wind farm operators and grid planners now incorporate ENSO state into their seasonal forecasts.
The United States has the world's second-largest installed wind capacity at roughly 150 GW, concentrated in a corridor extending from Texas through Oklahoma, Kansas, and into the upper Midwest. During El Niño winters, the polar jet stream strengthens and shifts southward across the southern tier of the country. This increases wind speeds at turbine hub height across Texas and the southern Great Plains. ERCOT, the Texas grid operator, has documented that its wind fleet's capacity factor runs 5-10% above seasonal norms during El Niño winters, with the effect strongest in the Panhandle and West Texas zones. The Midcontinent Independent System Operator (MISO), which covers the upper Midwest, sees the opposite — a 5-15% reduction in wind output as the jet stream shifts away from its normal winter position over the Dakotas and Minnesota. These regional shifts are large enough that grid operators with visibility into ENSO forecasts can adjust their resource adequacy calculations months in advance.
Northern Europe's offshore wind fleet — the UK's Dogger Bank, Denmark's Horns Rev, Germany's Borkum Riffgrund, and the Netherlands' Borssele zones — is sensitive to El Niño through the North Atlantic Oscillation (NAO). El Niño winters tend to push the NAO into its negative phase, which weakens the westerly wind belt across the North Sea. A 2022 study published in Environmental Research Letters analyzed 40 years of reanalysis data and found that European wind generation during El Niño winters was 8-12% lower than during neutral or La Niña winters, with the largest reductions in the December-February period when electricity demand peaks. For a region that has placed a large strategic bet on offshore wind — the EU's REPowerEU plan targets 300 GW of offshore wind by 2050 — the ENSO sensitivity of North Sea wind speeds is an underappreciated source of seasonal supply risk.
Brazil's Northeast wind corridor, which has attracted major investment from developers including Enel, EDP Renovaveis, and Casa dos Ventos, is also ENSO-sensitive. During El Niño, the northeast trade winds that drive this region's exceptional capacity factors (averaging 45-50%, compared to a global average of roughly 35%) tend to weaken slightly. The effect is modest — a 3-7% reduction in wind speeds at hub height — but it matters because Brazil's Northeast wind is paired with its hydro-dependent Southeast/Central-West grid. When El Niño simultaneously reduces hydropower and wind, the backup requirement compounds.
Hydropower: The Biggest Renewable Risk
Hydropower supplies roughly 16% of global electricity, more than wind and solar combined. A hydroelectric dam cannot be moved or diversified — it sits in one watershed and depends entirely on the precipitation falling into it. When El Niño redirects that precipitation elsewhere, output falls and grid operators must find replacement power. This is the largest single energy-sector impact of ENSO.
Brazil generates roughly 60% of its electricity from hydropower, with the Southeast/Central-West subsystem anchored by the Parana River basin providing the majority. El Niño brings drought to this region. During 2015-16, reservoir levels fell to roughly 30% of capacity and hydro generation dropped to 60-65% of rated output. Brazil's grid operator (ONS) dispatched thermal backup — natural gas and fuel oil — costing approximately R$2.5 billion ($800 million). ANEEL imposed a tariff flag adding R$0.045/kWh during the worst months.
The 2015-16 El Niño also pushed Colombia's hydropower system, supplying roughly 70% of the country's electricity, to its limits. Reservoir levels in Antioquia and Cundinamarca fell sharply, and spot power prices quadrupled. Venezuela's Guri Dam (10,200 MW, roughly 65% of national electricity) saw reservoir levels approach critical thresholds. The Guri crisis during 2009-10 — levels within 8 meters of minimum operating level — triggered nationwide blackouts lasting weeks.
Central and Southern Africa are consistently hit. The Kariba Dam on the Zambezi River, shared by Zambia and Zimbabwe (2,130 MW), fell to 12% of reservoir capacity during 2015-16. Both countries imposed 12-16 hours of daily load-shedding, cutting into mining output — roughly 10% of Zambia's GDP and 70% of export earnings. The African Development Bank estimated the combined economic cost at $500-700 million.
The Mekong River basin in Southeast Asia tells a different story. El Niño reduces dry-season flows, affecting run-of-river dams in China, Laos, and Cambodia. During 2015-16, dry-season flows at Stung Treng in Cambodia were roughly 25% below average, per Mekong River Commission data. The Xayaburi Dam in Laos (1,285 MW) saw capacity factors dip from roughly 50% to 35% during the driest months. East Africa is the exception: El Niño increases rainfall over Kenya, Tanzania, and Ethiopia, boosting hydropower. During 2015-16, Kenya's Seven Forks cascade ran 15-20% above average, and Ethiopia's GERD saw accelerated filling from above-average Blue Nile flows.
Grid Stability and the Backup Problem
The grid stability challenge during El Niño is that reductions hit multiple renewable sources simultaneously. A grid losing 15% of solar, 10% of wind, and 30% of hydropower at once faces a replacement gap only dispatchable thermal generation, demand response, or imports can fill.
California ISO's 2015-16 experience illustrates the dynamics. El Niño brought wetter, cloudier conditions, cutting utility-scale solar by 10-15%. But the same precipitation boosted hydro output 40% above the drought-depressed 2015 level. The net effect was positive: solar lost, hydro gained, gas plants throttled back. California's diversified portfolio provided ENSO resilience a less varied grid would lack.
Australia's National Electricity Market faces a harder challenge. Hotter, drier El Niño summers increase air-conditioning demand while reducing Snowy Mountains hydro output. During 2015-16, NEM spot prices spiked above A$10,000/MWh — the market cap — multiple times. The Australian Energy Regulator noted El Niño contributed to a 25% increase in average wholesale prices. When hydro fails during El Niño, replacement power typically comes from natural gas or coal. Brazil's thermal backup during 2015-16 added 15-20 million tonnes of CO2, roughly 3-4% of the country's annual emissions. An El Niño event intensified by climate warming forces more fossil fuel burning, which intensifies warming further.
The Economic Dimension
The economic cost of El Niño-driven renewable energy disruption flows through two channels. The first is the direct cost of replacement power. When hydropower output falls, grid operators dispatch thermal plants that are more expensive per megawatt-hour. Brazil's spot electricity price provides the most dramatic data point. During 2015-16, Brazilian spot prices in the Southeast/Central-West zone exceeded R$800 per MWh at peaks, compared to a normal range of R$150-200 per MWh — a 4-5x multiple. Industrial consumers on spot-indexed contracts absorbed these costs directly. Large consumers with fixed-price contracts were shielded in the short term but faced steep increases at contract renewal.
The second channel is the system cost of maintaining reliability margins. Grid operators must hold dispatchable capacity in reserve to cover the largest single contingency — typically the loss of a large generator or transmission line. During El Niño, when renewable output is depressed and variable, the required reserve margin increases because the system is already stressed. Holding additional thermal capacity on standby, even if it never runs, adds to system costs through capacity payments. The UK's National Grid ESO estimated that El Niño-related winter reserve costs added roughly 2-3% to total system balancing costs during affected winters.
For developing countries with limited fiscal space, the economic impact of El Niño energy disruption can be macroeconomically material. The broader El Niño economic impact on energy-importing countries in sub-Saharan Africa and South Asia is compounded when domestic hydropower fails and the replacement is imported diesel or LNG, pulling hard currency reserves into the power sector at the expense of other imports. The IMF has identified ENSO-aware energy planning as a low-cost resilience measure for hydro-dependent developing economies, noting in a 2023 working paper that incorporating ENSO forecasts into hydro reservoir management can reduce the cost of El Niño energy disruptions by 20-30%.
2026-2027 Outlook: Which Grids Are Most Exposed
The 2026-2027 El Niño forecast brings the renewable energy question into sharp focus for grid operators in hydro-dependent countries. Based on the projected intensity — NOA A CPC's 82% probability with RONI projections of +2.7 degrees Celsius — the event is expected to produce drought patterns broadly similar to 2015-16, with some amplification in Central America and northern South America.
Brazil enters this El Niño in a stronger hydrological position than it did in 2015. The Southeast/Central-West reservoirs are at roughly 65% of capacity as of mid-2026, compared to roughly 40% at the same point in 2015. Brazil has also added roughly 25 GW of wind and solar capacity since 2015, diversifying its generation mix and reducing the grid's marginal dependence on hydropower. But hydro still supplies more than half of Brazil's electricity, and a severe El Niño drought would still force thermal dispatch. Brazilian electricity sector analysts at PSR Energy Consultancy project that a strong 2026-2027 El Niño could increase the country's average spot price by 50-80% and add R$3-5 billion ($600-900 million) to total system costs.
Colombia and Venezuela are more vulnerable than Brazil. Both have less diversified grids and less fiscal capacity to subsidize electricity prices during a hydro crisis. Colombia's reservoir levels as of mid-2026 are near their seasonal average, but the Andean watersheds that feed the country's dams are forecast to see 30-40% rainfall deficits during a strong El Niño. The International Energy Agency's 2026 climate resilience assessment flagged Colombian hydropower as among the most ENSO-exposed energy assets globally.
The Zambezi basin countries — Zambia and Zimbabwe — face the most severe risk. Kariba Dam's reservoir level has been below 40% for much of 2025-2026 due to successive drought years, and a strong El Niño would push it toward the crisis thresholds seen in 2015-16. Both countries have increased solar investment — Zambia commissioned a 54 MW plant in 2024, and Zimbabwe has signed PPAs for roughly 200 MW of solar — but the new capacity represents a small fraction of the 2,130 MW at risk from Kariba. Load-shedding during a strong 2026-2027 El Niño could be severe, with economic consequences for the copper and cobalt mining sectors that are both countries' primary export earners.
Norway and the Nordic power market, as discussed in the Scandinavia article, have a more complex ENSO relationship. Norwegian hydropower, which supplies roughly 95% of the country's electricity, is sensitive to North Atlantic storm tracks that are modulated — but not dominated — by ENSO. The effect is variable enough that Norwegian grid operator Statnett does not treat El Niño as a primary planning variable, though it does incorporate the ENSO-influenced precipitation outlooks from the Norwegian Meteorological Institute into its seasonal hydrological forecasts.
For grid operators globally, the 2026-2027 event is a real-time test of whether ENSO-aware planning has moved from academic research to operational practice. The data and forecasting tools now exist. NOAA's CFSv2 model provides ENSO forecasts at 6-9 month lead times with enough skill for seasonal resource planning. The question is whether grid operators in hydro-dependent countries will use that lead time to secure backup generation, adjust reservoir management, and communicate price risk to consumers — or whether they will wait for the drought to arrive and manage the crisis in real time. The 2023-24 event showed that early preparation is cheaper than emergency response by a factor of roughly 3-to-1. The same arithmetic applies in 2027.