The potential for a major El Niño event developing soon, and for 2026 to be the hottest year on record.

The El Niño Southern Oscillation system is a major driver of the Earth's climate variations, driven by fluctuations in the temperature in the surface waters of the Pacific Ocean. This has two phases, El Niño, in which surface temperatures are high, and La Niña, in which they are low (although the Pacific is not always in one of these phases, there are neutral periods when neither occurs). The impacts of these oscillations are complex, but overall, the El Niño phase is associated with warmer global temperatures, while the La Niña phase is associated with cooler global temperatures. The warmest year on record, 2024, was associated with an El Niño phase.

In March 2026, the European Centre for Medium-Range Weather Forecasts began issuing warnings that the Pacific Ocean might be going to enter an El Niño phase in 2026. This is in some ways surprising, the ocean was still in a La Niña phase in March, and predictions made this early in the year are not usually considered reliable. Furthermore, less than three years had passed since the most recent El Niño phase, which is in itself unusual.

Map of sea-surface temperature anomaly issued in March 2026 and valid for June, July and August. European Centre for Medium-Range Weather Forecasts.

However, the El Niño Southern Oscillation system does not operate in isolation. The temperatures in the Pacific surface waters during the 2015-2016 and 2024 El Niño events were significantly higher than the 1997-98 event, which was the warmest event of the 20th century. Furthermore, the La Niña phases bracketing these 21st century events were much less extreme than those around the 1997-98 event (that is the surface waters did not cool as much), so these events were much less extreme in the sense that they did not drift as far from the average sea surface temperatures over a longer period. In fact, the three most recent La Niña phases have been accompanied by Pacific Ocean temperatures warmer than during the 1997-98 El Niño event.

On 15 April 2026 the UK's Met Office issued a warning that there was likely to be a severe El Niño event in 2026-2027, and on 14 May, the Climate Prediction Service of the United States National Weather Service also issued a press release warning that their predictions gave an 82% chance of the Pacific entering an El Niño phase between May and July 2026, with a 96% chance that El Niño conditions would exist between December 2026 and February 2027.

The reason behind the earliness and severity of these warnings is based upon a change in how predictions are made. Previously, predictions have been made upon the temperature of the surface of the ocean, which has not allowed for very long predictions. However, recent research has shown that a much more accurate, and longer-term, prediction can be made if the temperature of the top 300 m is used. 

In March 2026, the average temperature for the top 300 m of water in the central Pacific was already 1.0°C above baseline temperatures. This in itself is consistent with an El Niño, or even super El Niño event (an event, such as that in 1997-98, in which the surface waters of the Pacific are not just exceptionally warm, but at least 2.0°C warmer than the recent average sea temperatures). In the first week of April the temperature of these waters continued to rise sharply, reaching 1.6°C above baseline temperatures.

This has the potential to have a profound impact on the global average temperature. Predictions already suggested 2026 would be a hot year, with a 62% chance of being one of the four hottest years on record, and a 19% chance of being the hottest year (i.e. temperatures exceeding those of 2024). It has been suggested that there is a 30% chance of 2026 being the second year in which global average temperatures exceed 1.5°C above pre-industrial levels (defined as average temperatures between 1850 and 1900). The sharp increase in the temperature of the waters of the Pacific now makes these predictions look more-or-less inevitable.

An El Niño event has a number of profound affects upon the climate. South America tends to have much higher rainfall during El Niño events, while Indonesia, Australia, and Southeast Asia can suffer severe droughts. In India and Africa, rainfall patterns can be affected in less predictable ways, with some areas suffering high rainfall and flooding while others suffer severe droughts. Tropical storms become less common in the Atlantic, but more frequent in the Pacific. 

This is likely to have implications for food production in many parts of the world, with a combination of droughts and floods triggered by an El Niño event coming at the same time as fertiliser shortages triggered by Iran having closed the Straits of Hormuz in response to the Israeli and US attack earlier this year, making famine events likely. At the same time, the agencies which might provide relief during such events are suffering from a much reduced ability to act following the withdrawal of funding by the US, UK, France, Germany, and Japan. This is situation is also likely to be impacted by predicted rises in fuel prices, also triggered by the war in the Gulf of Persia, further limiting international agencies ability to respond to any crisis. 

A super El Niño event, starting from a base of record high sea temperatures, which now appears very likely, could have even more severe impacts. The super El Niño event of 1876 triggered a global famine which killed around 50 million people, about 3% of the world's population at that time. On this occasion the El Niño event caused the almost total collapse of the South Asian Monsoon, leading to the worst drought in 800 years, with concurrent droughts across Australia, Southeast Asia, Brazil, and North and Southern Africa (although it is also generally accepted that the high mortality rates in India were driven as much by the policies of the British colonial government as the drought itself).

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2025 on course to have been the joint-second-warmest year since records began.

With temperature measurements now available for eleven of twelve months, 2025 is currently tied with 2023 as the second-warmest year on record, with 2024 remaining the warmest recorded year, according to a press release issued by the European Copernicus Climate Change Service on 9 December 2025. November 2025 was the third warmest November on record (behind 2024 and 2023), with notably-warmer-than-average temperatures particularly prevalent over Canada and the Arctic Ocean. The month also saw a number of extreme weather events, including a series of tropical cyclones across Southeast Asia, which caused catastrophic flooding over a wide area.

Annual global surface air temperature anomalies (°C) relative to the 1850–1900 pre-industrial reference from 1967 to 2025. The value for 2025 is based on data for January to November. Copernicus Climate Change Service.

November 2025 was the third warmest November on record, with an average surface air temperature of 14.02°C, which was 0.65°C warmer than the November average for the period 1991-2020. It was, however, 0.20°C cooler than the average for the warmest November on record, in 2023, and 0.08°C cooler than the average for the second-warmest November on record, 2024. November 2025 was also 1.54°C above the estimated average temperature for the period 1850-1900, taken as the pre-industrial reference point. It was the second consecutive month to be more than 1.50°C above this reference, and the sixth such month in 2025, the figure having previously been exceeded in January, February, March, April, and October. It is now almost certain that 2025 will be one of the three warmest years since records began, unlikely to be warmer than 2024, but closely tied with 2023 to be the second-warmest year. It is possible that the average temperature for 2025 will not be 1.5°C above the pre-industrial reference, it is now almost certain that the average for the three year period 2023-2025 will be, the first recorded three-year period to be this warm.

Monthly global surface air temperature anomalies (°C) relative to the 1850–1900 pre-industrial reference period from January 1940 to November 2025, plotted as time series for each year. The year 2025 as well as the two warmest calendar years are shown in colour: 2025 in dark red, 2024 in orange, and 2023 in yellow. All other years are shown with thin grey lines. Copernicus Climate Change Service.

The global average temperature for the period September-November 2025 was the third highest on record, 0.67°C above the average for period 1991-2020, with only the years 2023 and 2024 having been warmer. The temperature was particularly warm over northern Canada, the Arctic Ocean, and Antarctica, but cooler than average over northeastern Russia.

The average land temperature over Europe was 5.74°C, 1.38°C above the average for the period 1991-2020, and making it the fifth-warmest November ever recorded in Europe. Temperatures were furthest above average over Eastern Europe, European Russia, the Balkan Peninsula, and Turkey. However, below average temperatures were encountered present over northern Sweden, Finland, Iceland, southern Germany, and northern Italy. Beyond Europe, temperatures were particularly high over both polar regions, northeastern Canada, the Canadian archipelago, the United States, the Arctic Ocean, and East Antarctica. Temperatures were notably below average over Siberia and northeastern Russia.

The period September-November 2025 was the fourth warmest such interval recorded in Europe, 1.06°C above the average for the period 1991-2020. Over this period, temperatures were notably warmer over Fennoscandia and European Russia, but near-average over Western and Central Europe.

The average sea surface temperature between 60° north and 60° south was 20.42°C in November 2025, making it the fourth warmest November measured by this metric, and 0.29°C cooler than the warmest recorded November, in 2023. Sea surface temperatures were particularly warm over the North Pacific, with record high temperatures recorded in the western North Pacific. However, temperatures over the central and eastern equatorial Pacific were near, or slightly below, average, probably due to a developing weak La Niña system. Record breaking temperatures were also recorded over the Norwegian Sea and the Coral Sea off the east coast of Australia.

Surface air temperature anomaly for November 2025 relative to the November average for the period 1991-2020. Copernicus Climate Change Service.

November was wetter than average across the UK, Ireland, Portugal, Spain, northwestern Russia, and much of the Balkan Peninsula, particularly Albania and Greece. The wet conditions over Western Europe were partly fuelled by Atlantic Storm Claudia. At the same time, Iceland, southern Spain, northern Italy, central Germany and Sweden, were drier than average, and conditions in southwestern Russia, Ukraine, and Turkey were close to drought level. Outside Europe, wetter than average conditions affected  the southwest USA, parts of northern Canada, northwestern Russia, Taiwan, southern Africa, Madagascar, and coastal regions of Australia. Flooding and related events, brought on by a combination of several tropical cyclones and a particularly heavy monsoon season, killed over 1100 people across South and Southeast Asia. At the same time, northern Mexico, the southeastern USA, much of western and central Asia, and southern Brazil had drier than normal conditions.

The period September-November 2025 was wetter than average across the UK, Ireland, most of Scandinavia, western Iberia and the southeastern part of Spain, and Central Europe. Romania and the Balkan Peninsula were drier than average in September, but wetter than average on October and November. Drier than average conditions were present over northern Italy, southern France, the larger  islands of the Mediterranean, and much of Eastern Europe including Turkey and western Russia. Much of Iberia remained dry, with persistently low soil humidity. Iceland began this period with dryer than average conditions, but ended with wetter than average conditions. 

Outside Europe, wetter than average conditions were prevalent from September to November over the western United States, Alaska, northwestern Mexico, the Korean Peninsula, eastern China, central Asia, southern Africa, Madagascar, the northern coast of Australia, and New Zealand. At the same time, drier than average conditions affected the southern and eastern United States, much of western Asia, southern Brazil and southeastern Australia. 

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2023 was officially the hotest year on record.

A study by NASA's Goddard Institute for Space Studies has confirmed that 2023 was the hottest year on record, according to a press release issued on 12 January 2024, with global temperatures averaging 1.2°C above the average for the period 1951-1980 (used as a baseline by NASA) and 1.4°C above the average from 1880-1990, which is also widely used as a baseline. Every month from June to December was the hottest that calender month has ever been, which is to say June was the hottest June ever recorded, July was the hottest July ever recorded, etc.. Furthermore, July 2023 was the hottest month ever recorded, with higher average global temperatures than recorded in any calendar month since records began.

This data visualization, which is updated monthly, shows the seasonal cycle of temperature variation on the Earth’s surface, and how those temperatures deviate from the average from 1951 to 1980. The data come from the GISS Surface Temperature Analysis and are publicly accessible here. The seasonal temperature offsets are based on the MERRA-2 reanalysis data here. NASA Scientific Visualization Studio.

The consequences of the extreme temperatures manifested themselves in a number of ways, including extreme heat, wildfires, intense rainfall, coastal flooding, and rising sea levels.

While the overall trend towards higher temperatures is driven by Human activity, and in particular the release of carbon dioxide from the burning of fossil fuels, yearly temperatures are also driven by natural phenomena such as volcanic eruptions and the El Niño - Southern Oscillation climate system.

Sea surface temperatures in the equatorial Pacific oscillate between two states, a warm El Niño phase and a cool La Niña phase. From 2020 until 2022 the equatorial Pacific was in a La Niña phase, which tends to supress global average temperatures. In May 2023 this switched to a warm El Niño phase, causing global temperatures to climb from that point. As the El Niño - Southern Oscillation climate system has the most influence during the Southern Summer, it is likely that the temperature elevation caused by this swing will be most strongly felt in February-April 2024. 

This map of Earth in 2023 shows global surface temperature anomalies, or how much warmer or cooler each region of the planet was compared to the average from 1951 to 1980. Normal temperatures are shown in white, higher-than-normal temperatures in red and orange, and lower-than-normal temperatures in blue. NASA Scientific Visualization Studio.

The climate in 2023 was also affected by the Hunga Tonga-Hunga Ha’apai undersea volcanic eruption in January 2022, one of the largest volcanic eruptions in recorded history, which pumped vast amounts of volcanic aerosols into the atmosphere. These aerosols reflect sunlight back into space, cooling the atmosphere, with the Hunga Tonga-Hunga Ha’apai eruption estimated to have caused a 0.1°C drop in atmospheric temperature in the Southern Hemisphere.

Independent studies by the National Oceanic and Atmospheric Administration in the US and the Hadley Centre in the UK both concluded that sea surface temperatures in 2023 were the highest recorded for any year since records began, corroborating the conclusions reached by NASA's Goddard Institute for Space Studies.

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At least five dead amid flooding and landslides in Vietnam.

At least five people have died and several more are missing in a series of flooding and landslide events in south and central Vietnam, after several days of continuous heavy rain associated with the southwest (summer) monsoon, which has affected Lam Dong, Bình Thuận, Bà Rịa–Vũng Tàu, Bạc Liêu, Cà Mau, An Giang, Hậu Giang, and Kiên Giang provinces. On Saturday 29 July 2023, a 47-year-old woman was swept away by flood waters in Bình Thuận Province, and was later found dead. On the same day a fishing boat off the same province's coast capsized in high winds, with one of the four crew, a 41-year-old man, missing since the event. A house collapsed amid high winds and heavy rain in Bạc Liêu Province, killing 36-year-old Dang Kim Men, and injuring her 37-year-old husband, Dang Van Dung and their eight-year-old son. A total of 59 nine houses are reported to have been destroyed in the province, and a further 52 to have lost their rooves. Three traffic police officers have been confirmed dead after a landslide hit the station at which they were based at in the Bảo Lộc Pass in Lam Dong Province, at about 2.30 pm local time on Sunday 30 July; a member of the public is still missing following the incident.

Rescue teams searching the site of a landslide in which three people are now known to have died and one is still missing in Lam Dong Province, Vietnam, on Sunday 30 July 2023. Vietnam Global.

Monsoons are tropical sea breezes triggered by heating of the land during the warmer part of the year (summer). Both the land and sea are warmed by the Sun, but the land has a lower ability to absorb heat, radiating it back so that the air above landmasses becomes significantly warmer than that over the sea, causing the air above the land to rise and drawing in water from over the sea; since this has also been warmed it carries a high evaporated water content, and brings with it heavy rainfall. In the tropical dry season, the situation is reversed, as the air over the land cools more rapidly with the seasons, leading to warmer air over the sea, and thus breezes moving from the shore to the sea (where air is rising more rapidly) and a drying of the climate.

Diagrammatic representation of wind and rainfall patterns in a tropical monsoon climate. Geosciences/University of Arizona.

Much of Southeast Asia has two distinct Monsoon Seasons, with a Northeast Monsoon driven by winds from the South China Sea that lasts from November to February and a Southwest Monsoon driven by winds from the southern Indian Ocean from March to October. Such a double Monsoon Season is common close to the equator, where the Sun is highest overhead around the equinoxes and lowest on the horizons around the solstices, making the solstices the coolest part of the year and the equinoxes the hottest.

The winds that drive the Northeast and Southwest Monsoons in Southeast Asia. Mynewshub.

This years rains have been unusually heavy across Southeast Asia, despite there being an El Niño system over the South Pacific, which would usually bring drier conditions. This is probably linked to the rising global temperature, with the record for the Earth's highest average temperature over a 24 hour period being broken three times in July, which has led to higher rates of evaporation from all oceans, leading to unusually high rainfall in many parts of the world.

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Record for global hottest day broken three times so far in July.

The record for the hottest average global temperature over a 24 hour period has been exceeded four times this so far in July 2023, according to the Climate Reanalyzer tool at the University of Main's Climate Change Institute. On Monday 3 July the average global temperature was 17.01°C, exceeding a previous global average of 16.89°C set on Monday 25 July 2022 by 0.11°C. On Tuesday 4 July the average global temperature reached 17.18°C, beating Monday's record by a further 0.17°C. Two days later, on Thursday 6 July, the temperature reached 17.23°C, exceeding Tuesday's temperature by a further 0.05°C, and the highest pre-July 2023 global temperature recorded by 0.34°C.

Average global temperatures between 1979 and 2023. Climate Reanalyzer.

The average temperature is warmest in the northern summer, as there is a greater land-area in the Northern Hemisphere, and the atmospheric temperature over land is more prone to short term variations. However, the long-term trend is largely driven by the Southern Hemisphere, where there is more ocean, as the ocean's both warm and cool more slowly, due to the higher thermal inertia of water (i.e. it requires more energy to heat water). The past few years have seen exceptionally high global temperatures, despite the presence of a La Niña system over the South Pacific (the cooler phase of a long term climatic oscillation). This year the South Pacific has switched into the El Niña phase of the same oscillation system, which is predicted to drive global temperatures upwards more sharply over the next few years, potentially driving the Earth's temperature over tipping points which could alter the long-term climate of the planet.

Recorded global temperatures on Saturday 8 July 2023. Climate Reanalyzer.

The El Niño is the warm phase of a long-term climatic oscillation affecting the southern Pacific, which can influence the climate around the world. The onset of El Niño conditions is marked by a sharp rise in temperature and pressure over the southern Indian Ocean, which then moves eastward over the southern Pacific. This pulls rainfall with it, leading to higher rainfall over the Pacific and lower rainfall over South Asia. This reduced rainfall during the already hot and dry summer leads to soaring temperatures in southern Asia, followed by a rise in rainfall that often causes flooding in the Americas and sometimes Africa. Worryingly climatic predictions for the next century suggest that global warming could lead to more frequent and severe El Niño conditions, extreme weather conditions a common occurrence.

Movements of air masses and changes in precipitation in an El Niño weather system. Fiona Martin/NOAA.

The Climate Reanalyzer is a climate visualization tool, rather than a model, which is to say it provides data on observed temperatures but does not attempt to make predictions from these. It draws data from a number of sources, including the National Oceanic and Atmospheric Administration and the European Copernicus Climate Change Service. As such it is not regarded as an official governmental source, but is considered a reliable source of information by climate scientists.

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