El Niño record strength: unprecedented ocean warming in 2026

How is the unprecedented El Niño record strength being measured?

The current El Niño has already broken historical records regarding daily sea surface temperature anomalies in the central-eastern Pacific. On 19 September 2026, temperatures in this key region were recorded at 3.05C above the long-term average. This figure exceeds the previous benchmark of 3.02C set during the exceptionally strong El Niño of 2015.

Scientists utilize different metrics to quantify the intensity of these climate events, which can lead to varying interpretations of how 'record-breaking' an event truly is. The primary metric used for the current announcement is the Oceanic Niño Index (ONI).

Understanding the ONI and RONI metrics

The Oceanic Niño Index (ONI) focuses on the deviation of sea surface temperatures from the long-term historical average in specific Pacific regions. When these temperatures consistently remain 0.5C above normal, an El Niño is officially declared. However, the ONI does not account for the general warming trend of the global oceans caused by climate change.

To address this, many forecasters in Australia and the United States employ the Relative Oceanic Niño Index (RONI). This index measures the temperature of the key El Niño region relative to the rest of the tropical oceans. Because the RONI factors in background warming, it provides a different perspective on whether an event is truly anomalous. By the RONI standard, the 2026 event has not yet broken records, though scientists expect more significant updates as the phenomenon approaches its peak later this year.

What is El Niño and how does it affect global temperatures?

El Niño is a naturally occurring climate pattern that typically emerges every two to seven years and generally persists for approximately one year. The phenomenon is driven by changes in the trade winds that normally blow from east to west across the Pacific Ocean. During an El Niño event, these winds can weaken or even reverse direction, allowing warm water to migrate eastward across the Pacific.

As this warm water shifts, it releases significant heat from the ocean into the atmosphere. This heat transfer acts as a catalyst for broader climatic shifts, often boosting global temperatures and altering traditional weather patterns across various continents. Professor Adam Scaife, Head of Long Range Prediction at the Met Office, noted that the current development is an "unprecedented event," highlighting that the record-breaking temperatures have been achieved several weeks before the expected peak.

What are the current global weather impacts of this event?

While the magnitude of an El Niño does not always guarantee a proportional impact on weather, many expected effects are already being observed worldwide. The phenomenon tends to increase the probability of extreme weather, such as floods and storms in certain regions, while simultaneously driving droughts and wildfires in others. These shifts can have profound consequences for global food security, crop yields, and national economies.

Specific regional impacts currently being monitored include:

• India: El Niño years are traditionally associated with below-average monsoon rainfall. According to data from the India Meteorological Department, the southwest monsoon had delivered 15% less rain than normal as of 22 September 2026.
• The Atlantic: Changes in high-altitude wind patterns often reduce hurricane activity in the Atlantic. In 2026, no Atlantic hurricanes have formed so far, setting a new record for the latest date without hurricane formation since the era of satellite monitoring.
• South America and the USA: There is an increased risk of flooding in coastal areas of Peru, Ecuador, and the southern United States.
• Southeast Asia and Brazil: Regions including Indonesia, Australia, and Brazil face an enhanced threat of drought and wildfires.

How might El Niño influence weather in the UK and Europe?

The influence of El Niño on the United Kingdom is less direct than in the tropical Pacific due to the vast geographical distance. However, the phenomenon is historically linked to increased chances of stormy and wet conditions across north-west Europe during the late autumn and early winter months.

The Met Office has already identified signals for increased rainfall and storminess in the UK for this autumn, with particular emphasis on the November and December period. Historical precedents suggest these impacts can be severe; the 2015–2016 El Niño coincided with a series of major storms that caused what experts described as the most extreme flooding on record in the UK.

The uncertainty of winter temperature shifts

While storminess is a common correlation, the impact of El Niño on UK temperatures remains a subject of scientific debate. While some El Niño years coincide with significant cold spells—such as the "Big Freeze" of 2009/2010—the historical evidence is mixed. For instance, the 2006/2007 winter was also an El Niño year but resulted in unseasonably warm conditions. Consequently, while the current event is exceptionally strong, its exact influence on UK winter temperatures cannot be definitively predicted.

Key takeaways

• The 2026 El Niño has set a new record for daily sea surface temperature anomalies at 3.05C.
• The Oceanic Niño Index (ONI) confirms this exceeds the previous 2015 record of 3.02C.
• India is already experiencing 15% less monsoon rainfall than normal due to the phenomenon.
• Atlantic hurricane activity has hit a record low for this time of year in 2026.
• The Met Office warns of increased rainfall and storminess for the UK this autumn.

FAQ: El Niño record strength

What is the difference between ONI and RONI?

The Oceanic Niño Index (ONI) measures sea surface temperature deviations from the long-term average. The Relative Oceanic Niño Index (RONI) measures these temperatures relative to the rest of the tropical oceans, accounting for the background warming caused by global climate change.

Why is the 2026 El Niño considered unprecedented?

It is considered unprecedented because it has already broken the sea surface temperature record (3.05C) several weeks before reaching its expected peak. This indicates an extreme level of ocean warming compared to previous recorded events like the 2015 El Niño.

How does El Niño affect hurricane seasons?

El Niño typically reduces hurricane activity in the Atlantic Ocean by altering wind patterns high in the atmosphere. In 2026, the lack of Atlantic hurricanes has set a new record for the latest date without storm formation since satellite monitoring began.

Will El Niño cause more droughts or floods?

It causes both, depending on the region. It increases the risk of floods in coastal Ecuador, Peru, and the southern USA, while increasing the threat of drought and wildfires in Brazil, Australia, and Indonesia.

Can El Niño predict UK winter weather?

It can signal increased storminess and rainfall in north-west Europe during late autumn and winter. However, its impact on temperature is inconsistent, sometimes causing cold spells and other times resulting in unseasonably warm winters.