Scientists watching the tropical Pacific say the coming swing in ocean temperatures could nudge global weather into a rougher phase, stacking on top of human‑driven warming and reshaping rainfall, heatwaves and storms from the US to Europe.
From record heat to a fresh climate jolt
Global climate records were smashed in 2024. Heatwaves grew longer, oceans ran hotter than ever, and many regions felt like they had skipped a season. That spike was not just bad luck.
Two forces acted together. One is long‑term global warming from greenhouse gas emissions. The other is a powerful natural cycle in the Pacific Ocean, known as ENSO – the El Niño–Southern Oscillation.
- Human‑driven emissions raised the background global temperature.
- An intense El Niño added an extra layer of heat to atmosphere and oceans.
When those two trends align, as they did recently, the result is a step change that many people felt directly: hotter nights, failed crops, record wildfire risk and stressed power grids.
What El Niño and La Niña actually do
ENSO has two main phases and sometimes neutral pauses between them. It plays out in the tropical Pacific but sends ripples through the entire climate system.
El Niño: when Pacific waters overheat
During El Niño, sea surface temperatures in the central and eastern equatorial Pacific rise above average. Warmer water alters wind patterns, cloud cover and storm tracks.
El Niño years tend to push global temperatures to new highs, on top of long‑term warming.
The most recent El Niño ran roughly from spring 2023 to spring 2024. It supercharged the already warming climate, helping 2024 become the hottest year yet in the instrumental record. Many regions experienced:
- Hotter global average temperatures
- Increased marine heatwaves and coral bleaching
- Altered monsoon behaviour in Asia and Africa
- Disrupted rainfall in South America and Australia
La Niña: the cool counterpart with sharp impacts
La Niña is the cooler flip side. In this phase, a broad stretch of the tropical Pacific becomes cooler than average. Trade winds strengthen, and warm water piles up towards the western Pacific.
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La Niña years tend to be cooler than El Niño years. Yet “cooler” does not mean safe or calm. In a world where baseline temperatures keep rising, La Niña can still bring new extremes.
A strong La Niña can amplify droughts in some regions and flooding in others, even while slightly reducing global mean temperature.
Historically, La Niña has been linked with:
- Wetter conditions and stronger hurricane seasons in parts of the Atlantic basin
- Drier, hotter conditions in the southern US and parts of South America
- Heavier rainfall and flood risk in Southeast Asia and Australia
Why 2026 is catching scientists’ attention
Climate centres tracking Pacific temperatures now see signs that the ENSO cycle is moving again. After the recent El Niño faded, the system began shifting towards cooler conditions in the tropical Pacific. Forecasts point to a likely La Niña phase developing and then maturing towards 2025–2026.
On its own, a La Niña would slightly cool the global average compared with an El Niño year. But that cooling sits on top of a dramatically warmer baseline created by decades of emissions.
The concern is not a return to “normal”, but a transition into a different flavour of extremes shaped by a cooler Pacific and a hotter planet.
Models suggest that by 2026, the climate system could be in a configuration where La Niña‑style patterns dominate for a time, redirecting jet streams and shifting storm corridors across the globe.
What this could mean for Europe and the US
Shifting risks for Europe and France
The Pacific sits far from Europe, yet its pulses can bend the atmospheric flow over the North Atlantic. Changes in ENSO often influence the position and strength of the polar jet stream, which steers storm systems towards or away from the continent.
During La Niña episodes, past years have seen tendencies for:
- Increased blocking patterns over parts of Europe, which can lock in hot or dry spells
- More frequent winter cold snaps when Arctic air is displaced southward
- Shifts in storm tracks that can leave some regions parched and others repeatedly soaked
For France, this can translate into a volatile sequence: a very mild winter, then a sharp cold outbreak, followed by a hot, dry summer with localised severe storms. French forecasters are watching these signals closely as they update seasonal outlooks for the next couple of years.
North American weather on a different track
In the US and Canada, La Niña is often linked with a more active Atlantic hurricane season, because wind patterns become more favourable for storm development. It can also bring:
- Drier, hotter conditions in the southern tier of the US
- Cooler, wetter weather in the Pacific Northwest
- Increased wildfire risk in the US West and parts of Mexico
Against a warmer climate backdrop, those tendencies can escalate into tangible hazards: more days of extreme heat, stressed water supplies, and a longer fire season in vulnerable regions.
When natural cycles meet human warming
The coming Pacific swing matters most because of the way it interacts with long‑term warming. ENSO has always been part of Earth’s climate machinery. What has changed is the starting point.
Today, both El Niño and La Niña unfold in a climate that is already about 1.2–1.3 °C warmer than in the late 19th century.
This means that:
- El Niño years now push global averages closer to or above 1.5 °C for brief periods.
- La Niña years, once relatively cool, now resemble “normal” conditions from just a few decades ago.
- Extreme rainfall, heatwaves and droughts are more likely for the same ENSO signal strength.
| Phase | Global temperature effect | Typical regional impacts |
|---|---|---|
| El Niño | Warmer than trend | Heatwaves, marine heatwaves, drought in some tropics, floods elsewhere |
| Neutral | Close to trend | Less predictable, background warming still strong |
| La Niña | Slightly cooler than trend | More Atlantic hurricanes, flood risk in parts of Asia, drought in others |
What people and planners should watch for
As the Pacific cools and La Niña patterns emerge, there are several practical signals worth tracking.
- Updates from major climate centres on ENSO forecasts, usually issued monthly.
- Seasonal outlooks for rainfall and temperature at national weather services.
- Indicators of compound risks: heat plus drought, or heavy rain on already saturated ground.
- Strain on energy systems as heating or cooling demand spikes during extended extremes.
Local impacts depend strongly on geography. A farmer in southern France worries about summer heat and water shortages. A city planner in London focuses on flood‑ready infrastructure if winter storms intensify. In the US Midwest, timing of rainfall against critical planting windows can make or break a season.
Key terms and future scenarios
Understanding a few useful concepts
ENSO: The El Niño–Southern Oscillation is a recurring pattern of temperature and wind changes in the tropical Pacific, swinging between warm (El Niño), cool (La Niña) and neutral phases on timescales of two to seven years.
Baseline warming: This is the underlying long‑term rise in global temperature caused mainly by greenhouse gases. Natural cycles move temperatures around this rising baseline, sometimes pushing them briefly above agreed‑upon thresholds.
Plausible paths for the late 2020s
Climate models give broad scenarios, not precise daily forecasts. For the late 2020s, they point towards a few recurring patterns:
- Short windows in La Niña years where global averages dip slightly, tempting some to say warming has paused.
- Rapid rebounds into new record territory with the next El Niño, as stored ocean heat is released.
- Growing pressure on food systems as rainfall belts shift, forcing adjustments in crop choices and timing.
For individuals, the Pacific may feel distant, but its mood shapes daily life: food prices, insurance costs, holiday weather, and even public health through heat stress and air quality. As 2026 draws closer and signals in the Pacific sharpen, the balance of risks is tilting towards a more erratic, testing climate phase rather than a return to calm.
