The strongest start on record
The El Niño that the World Meteorological Organization declared on 2 June is the strongest ever measured for its time of year. Forecasters expect it to peak in November or December and then weaken slowly. The agency puts the chance that it persists through February 2027 at close to 100%, a level of confidence it has not used before for either El Niño or La Niña.
El Niño lifts heat from the equatorial Pacific into the atmosphere and moves rainfall patterns thousands of kilometres away. This one is running on an ocean that was already unusually warm, which is why its effects are expected to be larger than its raw strength suggests.
Records are already falling
In August, the Copernicus Climate Change Service recorded the highest average sea surface temperature between 60 degrees north and 60 degrees south: 21.11C, above the previous record of 21.09C set in March 2024. The service linked the figure to heat added by El Niño on top of decades of human-driven warming.
Scientists expect 2026 to close as the hottest year measured. The last two months have each set global heat records, and the peak of the event is still ahead.
What it means on the ground
The pattern raises the risk of drought and fire in the Amazon, Canada, the western United States and parts of Australia, where vegetation grown during wet years dries out quickly when heat returns. It also points to heavy rain and flooding in other regions, including a wet winter on the US west coast.
California is preparing for record-warm coastal water and a run of king tides on 24 to 26 November, 22 to 25 December and 20 to 23 January. Those tides can flood low-lying roads even on calm, sunny days, and a single storm on top of them could push water higher still.
The event will shape the COP31 talks that open in Antalya, Türkiye, on 9 November. Negotiators arrive with the overshoot of the 1.5C limit now treated as unavoidable and with a year of disasters behind them. El Niño will fade. The heat it leaves in the record books will not.