The Met Office has warned that the El Niño event currently developing over the Pacific Ocean is likely to be the strongest in living memory, with the potential to push global temperatures to unprecedented levels. Combined with human-induced climate change, forecasters say it is "very likely" to make 2027 the hottest year on record, while also raising the risk of extreme weather worldwide, including a wetter, stormier fell autumn for the UK.

Scientists declare an El Niño when Pacific sea surface temperatures rise 0.5C above average, but current readings are already more than 2C above normal and could exceed 3C at their peak later this year, a level unseen since records began in 1950 and possibly the strongest since the 19th century. Some climate groups predict anomalies could reach 4C, which researchers say might make it the strongest such event in 500 to 1,000 years. Effects are already visible, including below-average monsoon rains in South Asia, suppressed Atlantic hurricane activity with only three named storms so far this season, and heightened risks of drought and bushfires in Australia and flooding in Peru, Ecuador and the southern United States.