Fact check: What are El Niño and La Niña and could they impact the climate in 2025?

The past year is certain to be the hottest on record, according to European scientists, and the first to see average global temperatures surpass the Paris Agreement target of 1.5 degrees Celsius above the pre-industrial period.

Soaring temperatures in 2024 were partly boosted by climate conditions known as El Niño (Spanish for "the boy"), according to the World Meteorological Organisation’s data analysis.

In 2025, another phenomenon known as La Niña (Spanish for "the girl") could emerge to slightly cool global temperatures, meaning it looks unlikely that the 2024 temperature record will be broken next year.

But despite this, 2025 is still likely to be among the three hottest years on record, according to the UK’s weather and climate agency, the Met Office.

El Niño and La Niña are two opposing climate conditions in the Pacific Ocean that affect the weather across the globe.

Trade winds in the Pacific tend to blow from east to west, pushing warm surface waters towards the western Pacific.

El Niño occurs when these winds weaken or reverse, making the waters in the eastern Pacific - off the coast of the Americas - warmer than normal.

In La Niña periods, the east-to-west trade winds become stronger, pushing warm waters further west towards the coasts of Australia and south-east Asia. This causes cold water to ‘upwell’ or rise from the depths of the ocean, making sea surface temperatures cooler on average, particularly in the Americas.

The episodes happen at irregular intervals every two to seven years, and usually last nine to 12 months.

Both El Niño and La Niña can affect weather patterns across the world. Although each episode is different, La Niña is associated with rainier-than-normal conditions in several parts of the world, such