El Niño Becomes Strongest on Record, Triggering Global Weather Shifts

The developing El Niño climate phenomenon has become the strongest on record, according to scientists who monitor Pacific Ocean temperatures. Daily sea surface temperatures in a key region of the central-eastern Pacific reached 3.05C above average on September 19, surpassing the previous record of 3.02C set during the strong El Niño of 2015. While some longer-term measures have not yet reached record levels, this is expected to change as the phenomenon's peak is not anticipated until later this year.

El Niño is a naturally occurring climate pattern that occurs approximately every two to seven years and typically lasts for about a year. It involves a weakening or reversal of trade winds that usually blow east across the Pacific Ocean, allowing warm water to spread eastward. This process releases heat from the ocean into the atmosphere, which can elevate global temperatures and alter weather patterns worldwide.

Forecasters track El Niño's development by monitoring temperatures in a specific Pacific Ocean region. An El Niño is declared when these temperatures consistently remain 0.5C above normal. The strength of El Niño can be measured in different ways. The records now broken relate to daily sea surface temperature measurements compared to the long-term historical average, a metric known as the Oceanic Niño Index (ONI). Some scientists also use an alternative measure, the Relative Oceanic Niño Index (RONI), which compares the El Niño region's warmth to that of the broader tropical oceans, accounting for background warming from climate change. By the RONI index, the current El Niño is not yet a record-breaker, but further announcements are anticipated.

Professor Adam Scaife, Head of Long Range Prediction at the Met Office, stated, "We have been signalling for months that the developing El Niño will be an unprecedented event. The fact that it has already exceeded previous records – with several weeks to go before it peaks later this year – shows the enormity of this El Niño."

While every El Niño is unique and its impacts on global weather patterns are not guaranteed, the strength of this event suggests significant consequences. Professor Scaife noted, "Scientists are still assessing whether the impacts will be in proportion to its magnitude, but we are already seeing expected effects worldwide." El Niño typically increases the likelihood of storms and floods in certain regions while contributing to drought and wildfires in others.

Typical effects observed include below-average monsoon rainfall in India, which has already seen 15% less rain than normal as of September 22. Reduced hurricane activity in the Atlantic is another common impact due to altered atmospheric wind patterns. The year 2026 has seen no Atlantic hurricanes to date, marking the latest start for hurricane formation since satellite monitoring began. Other potential effects, some of which are already occurring, include an increased risk of floods in coastal areas of Ecuador, Peru, and the southern United States, alongside an enhanced threat of drought and wildfires in Brazil, Australia, and Indonesia. These weather shifts can have significant repercussions for crop yields, food security, and global economies.

The UK, situated far from the tropical Pacific, experiences less direct El Niño effects. However, it can contribute to a higher chance of wet and stormy conditions across northwest Europe in late autumn and early winter. A Met Office forecast indicated "signals for increased rainfall and storminess in autumn here in the UK," particularly in November and December. The winter of 2015-2016, coinciding with a very strong El Niño, brought severe flooding in the UK, described by experts at the time as the most extreme on record. El Niño can also be associated with cold spells in the UK during late winter, although this link is not consistently strong. For instance, the unseasonably warm winter of 2006-2007 coincided with an El Niño, while the "Big Freeze" of 2009-2010, the coldest in three decades, also occurred during an El Niño year. As this unprecedented El Niño approaches its peak, scientists will continue to monitor its development and global weather impacts.