Not every event is the same, and the consequences vary from region to region.

However, scientists have observed some common effects:

Temperatures

Global temperatures typically increase during an El Niño episode, and fall during La Niña.

El Niño means warmer water spreads further, and stays closer to the surface. This releases more heat into the atmosphere, creating wetter and warmer air.

But the regional effects are complicated, and some places may be both warmer and cooler than expected at different points in the year.

The hottest year on record, 2023, was boosted by El Niño conditions, on top of long-term human-caused climate change, and that warmth continued into 2024.