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How will El Niño affect the world?

From Australia to California, the UK to Peru, turbulent weather is on the way  

By Madeleine Cuff

A year of extraordinary weather

The world is entering uncharted territory as the record-breaking El Niño continues to gather strength in the tropical Pacific.

This vast release of heat and moisture from the ocean is expected to severely warp weather patterns around the world, leading to intense heat and drought in some areas, and torrential rain, hurricanes and storm surges in others.

"The tropical Pacific is a very influential part of the global oceans," says at the University of California. "It has an outsized ability to affect the global climate."

Broadly speaking, El Niño has two main impacts. The first is to push up global air temperatures around the world, as heat released from the Pacific Ocean makes its way into the atmosphere. That means 2027 is nearly certain to be the hottest year on record, and countries around the world are bracing for prolonged, dangerously high temperatures.

"We will see, with almost virtual certainty at this point, record-breaking global temperatures later this year, 2026, and almost certainly in 2027," says Swain. "That is actually a fairly remarkable statement, given that we've seen record-breaking temperatures so often in recent years."

The second impact is changes to the global hydrological cycle. El Niño changes atmospheric circulation patterns, shifting the location and timing of rainfall. That produces heavy rain and flash flooding in some areas, and severe drought in others.

These twin impacts will occur against the backdrop of a warming world. A warmer atmosphere holds more moisture, which makes the rainfall and drought effects of El Niño even more pronounced, while global temperatures are pushed even higher than they would otherwise be.

"El Niño kind of acts as a mini, sudden climate change on top of the not-so-mini, not-so-sudden, climate change we've already seen," says Swain.

These factors set the stage for a year of extraordinary weather around the world. Here is what to expect, and where.

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Click regions to explore the impacts of El Niño

[[#west coast]]

California and the US West Coast

In the Pacific Northwest, from Oregon and Washington and into Canada, El Niño is expected to bring drier-than-normal weather, which could produce drought conditions.

But it is California that will feel the most extreme impacts in this region, with the odds of a very wet winter "greatly elevated" says Swain, with more heavy rain and winter storms expected. Meanwhile, sea levels along the California coast rise sharply under an El Niño, due to what is known as a Kelvin wave, which is triggered by weakening trade winds in the Pacific. This can temporarily raise sea levels along the Californian coast by 15 to 30cm.

The threat is increased this year because California is at a peak of an 18-year tide cycle, bringing very high tides to the coast. A King tide coupled with a large winter storm could bring very severe impacts, with risk windows for the tides in November, December and January – including on Christmas Day. Highly populated areas such as the shoreline around San Francisco Bay, an area that includes international airports, are among the most at risk.

"The likelihood of significant flooding [in California] will be much higher than usual," says Swain. "There is already significant coastal erosion. There are coastal homes being eroded and falling into the ocean. The beaches are disappearing. There's significant concern that the Pacific Coast Highway may be underwater or undermined and eroded this winter."

In light of the severe threat, on 21 September California's governor Gavin Newsom to intensify efforts to prepare for El Niño impacts. State agencies are working to protect vulnerable communities and move resources and equipment like pumps and sandbags into position across the state.

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[[#central america]]

US East Coast and Gulf of Mexico

El Niño tends to deliver a quiet hurricane season in the North Atlantic, and that is certainly true so far this year. No major hurricanes have formed in the basin so far – the longest hurricane-free start to a season in the satellite record.

But that may not mean an entirely calm winter season, particularly for residents of Florida. Hurricanes may be thin on the ground, but the number of tornadoes hitting central and south Florida per year roughly an El Niño year, analysis shows.

Meanwhile, "we expect wetter, stormier conditions generally from November to March under El Niño," says at Florida International University. That could lead to flooding, both from heavy rain and storm surges. "People should be ready for it," he says.

Florida is particularly vulnerable to groundwater flooding because its porous limestone geology is like "swiss cheese", says Obeysekera. "The [sea]water will come through the aquifer and push up the groundwater," he says. That could contaminate drinking water supplies, or flood domestic septic tanks and flush the faecal pollution out to delicate coastal habitats, he warns.

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[[#europe]]

UK and Europe

For the UK and northern Europe, the impact of El Niño on weather patterns is less pronounced, because the connection to the tropical Pacific is weaker and more convoluted.

The main effect for a strong El Niño is a higher chance of a wet and stormy start to winter. This could bring some much-needed consistent rain to replenish groundwater and reservoirs after the long summer drought, but also increases the risk of winter flooding.

Food prices are also likely to be impacted. The cost of goods such as rice, coffee and cocoa may increase, as these foodstuffs are grown in regions that can be severely affected by El Niño.

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[[#south america]]

South America

Peru is a nation on the front lines of El Niño, losing up to 5 per cent of its national income during El Niño years as a result of lower fishing catches and falling crop yields. The nation can be hit by torrential rainfall and high levels of snowmelt, which can trigger flash floods and landslides. that more than a million people are at risk from El Niño impacts across the country this year, and many local authorities across the country have declared a state of emergency.

In other parts of South America, such as the Amazon rainforest, El Niño makes drought and wildfires more likely. But for Venezuela and other countries to the north of the continent, the drying impacts of El Niño are being mitigated by increased rainfall across the rest of the year, says at the Venezuelan Institute for Scientific Research. He says high sea temperatures in the tropical Atlantic are driving above-average rainfall to northern countries, with modelling suggesting this will outweigh the drying impacts of El Niño over the course of the year.

Rather than drought, high temperatures are the real worry, he says. "The temperature is going to be a very important issue here in northern South America. That's going to be a health issue, that's going to be an energy problem – energy consumption is going to rise very much," he says.

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[[#east asia]]

Asia Pacific

Across the Asia Pacific region, heat is the most immediate threat from El Niño, causing disruption to agriculture, electricity demand, outdoor work and health services simultaneously.

But in some countries, changes to rainfall patterns are of equally serious concern. India is one of the first countries to feel the impact of El Niño, which tends to disrupt the June-September monsoon season. This year monsoon rainfall is 15 per cent below normal, threatening key crops and raising the risk of inflated food prices over the coming months. Risks of extreme heat, drought and water stress extend across South Asia, including Pakistan, Sri Lanka, Bangladesh and Nepal. This could have long-lasting consequences for water availability and food prices.

In Indonesia, hot, dry weather has led to huge wildfires that have blanketed South-East Asia in toxic fumes, posing a public health risk and threatening agriculture and fisheries. Some 175,000 people in Indonesia have suffered from respiratory illness since August, according to the country's health ministry.

"The central message is that El Niño is a risk multiplier," says at City University of Hong King. "Heat, drought, wildfire, smoke pollution, water scarcity and food insecurity can reinforce one another. These compound effects are often more damaging than any single hazard."

"We have experienced strong El Niño events before, but not one potentially this strong against today’s level of human-caused warming, widespread excess ocean heat and increased atmospheric moisture," he adds. "We are entering climatic territory for which there is no exact precedent."

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[[#africa]]

Africa

Drought in East and southern Africa is one of the clearest and most consistent El Niño signals, whilst warmer, wetter weather is more likely in the Greater Horn of Africa.

Both could wreak havoc on food supplies in the region. Analysis published 22 September by the charity Save the Children that 8 million children across East and southern Africa could be facing acute hunger by early next year, a rise of 30 per cent on current levels. The charity warns that countries such as Kenya and Somalia will see their food production hit by El Niño-related flooding, while countries such as Zambia and South Sudan are already suffering drought and extreme heat.

Extreme temperatures are likely to hit next year, says at the University of Reading in the UK. "I'm quite concerned about heatwaves in West Africa, all the way across to South Sudan, in March, April next year, when we would expect that normal heat season," she says.

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Australia and New Zealand

In Australia, El Niño tends to bring drought and heat, particularly to the eastern parts of Australia. This could bring major bushfires - the latest bushfire outlook, released August 17, reports an increased risk of fire across several parts of the country. "Australia has to watch out carefully for drought," says , formerly at the US National Center for Atmospheric Research (NCAR).

The influence of El Niño on Australian weather is most acute in August, September and October. Temperatures across the country have been warmer than normal in recent weeks and that is forecast to continue through until December, according to Australian government forecasts.

 Meanwhile in New Zealand, cooler weather is prevailing. "In New Zealand, we're one of the places that is actually a little cooler than normal during El Niño conditions," says Trenberth. "We're certainly experiencing that now… there's been snow this past week in New Zealand."

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