NASA satellites show this year's El Niño looks like the giant of 1997
NASA sea-height maps suggest the 2026 El Niño rivals the strongest in the satellite record. How El Niño works, frame by frame, and what it usually means for Australia.
This year's El Niño is shaping up as one of the strongest in the satellite record, and NASA scientists say its pattern in the Pacific looks a lot like the huge event of 1997-98.
In a new article, NASA Earth Observatory compares satellite maps of sea height across the Pacific Ocean from October 1997, October 2015 and October 2026. The current El Niño, it says, "rivals these past heavyweights".
How it works, frame by frame
Frame 1: a normal year. In the Neutral phase, trade winds blow from east to west along the equator, pushing warm surface water towards the western Pacific, north of Australia. In the east, cooler water rises from below, a process called upwelling, which keeps the surface cool off South America. The Bureau says the western tropical Pacific is normally 8–10 °C warmer than the east. The warmest water builds up north of Australia, bringing cloudiness and rainfall, the Bureau says. Air rises to Australia's north and sinks near South America, a huge connected loop the Bureau calls the Walker Circulation.
Frame 2: the winds ease. NASA explains every El Niño as a feedback loop between the ocean and the atmosphere. Trade winds normally keep warm water piled up in the western Pacific, where it stands higher than in the east. When those winds weaken, the warm water begins to pulse eastward.
Frame 3: El Niño. The eastward shift further weakens, and sometimes reverses, the winds, letting even more warm water move east. Warm water builds up in the central and eastern Pacific, and the cloud and rain shift with it, away from Australia and towards South America. The Bureau says that once an El Niño starts, the weaker winds and warmer east tend to reinforce each other, so it tends to persist.
Frame 4: what satellites see. Water expands as it warms, so satellites that measure the height of the sea surface can see the heat building. Higher-than-normal sea levels in the central and eastern equatorial Pacific are a sign of El Niño.
What El Niño usually means for Australia
Frame 5: what it means here. According to the Bureau of Meteorology, El Niño typically brings:
- below-average winter–spring rainfall for eastern parts of the country, and a greater risk of drought for northern and eastern Australia
- a later start to the northern wet season
- higher temperatures and more heatwaves
- clearer nights and a longer frost season
- fewer tropical cyclones.
The Bureau says the greatest impact is usually in winter and spring. But it also stresses that "no two events, and no two sets of impacts, are exactly the same", and that ENSO "is only one factor in a complex system that influences Australia's climate".
Around the world
The last two very strong events, in 1997-98 and 2015-16, upended weather around the world, NASA says, from fires in Indonesia and the Amazon to drought and crop failures in southern Africa and heavy rain and coastal flooding in Southern California.
This year looks like 1997
NASA's maps compare 13 October 1997 (from the TOPEX/Poseidon satellite) with 12 October 2026 (from Sentinel-6 Michael Freilich). Red shows sea levels above average, white is normal and blue is lower.
"What's unique about altimetry is that we have a 35-year record from nearly identical satellites flying almost the same ground track, with each mission overlapping the next," said Josh Willis, project scientist for sea level missions at NASA's Jet Propulsion Laboratory (JPL). "That lets us look back in time and compare this El Niño to what happened in 1997. And right now, this one is on track to be even bigger."
NASA says the 2026 El Niño came on much more suddenly than 1997-98. But as of October the two look similar in character: sea level low in the west and high in the east, and high, warm water reaching all the way to South America. Willis thinks the impacts could be similar too.
The 2015-16 event was also very strong but different. Less of the warm, high water reached the coast of South America, and in the northern winter that followed, rainfall was concentrated more over Central America and the south-eastern United States, with significant flooding in Mexico.
The El Niño outlook from the US National Oceanic and Atmospheric Administration (NOAA) on 8 October gave an 83 per cent chance of a strong-to-very strong El Niño through the first three months of 2027. Willis notes that El Niño's influence travels through a chaotic atmosphere, and the signal can get muddled as it extends beyond the tropics.
"There's always a bit of a dice roll here," he said. "Just because this El Niño looks like 1997 doesn't mean it will be exactly the same—it's just our best guess at the moment."
What the Bureau says now
NASA's article looks at the Pacific and the Americas and does not discuss Australia. The Bureau of Meteorology's Climate Driver Update, issued on 13 October, says "El Niño is at near-record levels", with the warmth in the tropical Pacific forecast to peak around November or December and last into autumn 2027.
The Bureau also notes that a strong El Niño signal "does not necessarily mean strong impacts on Australian rainfall and temperature", because El Niño is only one of many factors in Australia's weather. It points to its long-range forecast as the best guide.
- NASA article and maps: El Niño Then and Now
- Bureau of Meteorology: Climate Driver Update
- Bureau of Meteorology explainer: El Niño and La Niña
Sources: “El Niño Then and Now”, NASA Earth Observatory, 23 October 2026; Bureau of Meteorology Climate Driver Update, 13 October 2026; Bureau of Meteorology, “El Niño and La Niña” (updated 24 September 2025). Adapted from “El Niño Then and Now”, NASA Earth Observatory, 23 October 2026. NASA content is in the public domain; no endorsement by NASA is implied. Story by Kathryn Hansen; maps by NASA Earth Observatory/Lauren Dauphin, using altimetry data provided by NASA/JPL-Caltech. Freeze-frame illustrations: The Dosage, made with AI tools.