El Niño is the warm phase of the El Niño Southern Oscillation, a periodic warming of the central and eastern Pacific Ocean [1, 2, 3].

This phenomenon matters because it reshapes global weather patterns, often leading to significant climatic shifts that affect agriculture, disaster preparedness, and public health across multiple continents.

The process begins when trade winds weaken, which allows warm water to accumulate in the central and eastern Pacific [1, 2]. This shift in ocean temperature alters atmospheric circulation, creating a ripple effect that influences weather worldwide [1, 2].

These events are not constant but occur periodically. El Niño typically develops every two to seven years [1] and can last between nine and 12 months [1, 2]. These cycles often form during the boreal winter [1, 2].

While modern science now monitors these shifts with satellite data and ocean buoys, the phenomenon has been known for centuries. South American fishermen first noticed the warming patterns in the 1600s [4].

The center of the phenomenon remains fixed in the central and eastern Pacific Ocean [5, 2]. Because the ocean and atmosphere are deeply linked, the heat released from the water into the air changes how storms move and where rain falls, often bringing drought to some regions and flooding to others [1, 2].

“El Niño typically develops every two to seven years”

The recurring nature of El Niño demonstrates the profound link between ocean temperatures and global atmospheric stability. Because the phenomenon operates on a predictable yet variable cycle, its onset serves as a critical signal for governments to adjust food security strategies and emergency management to mitigate the risks of extreme weather.