How does El Nino Affect Weather

El Niño is a period of very high temperatures in the Pacific Ocean. El Niño literally means “the boy” referring to the child Jesus because El Niño often occurs during Christmas season. El Niño can affect weather disturbances in different regions of the world.  It is believed that the warming of the ocean’s surface temperature is caused by global warming.

Weakening of trade winds

During non-El Niño conditions, trade winds push warm water westward allowing the cooler water from the deep level to rise up. The nutrient-rich cold water supports the ecosystem. One of the signs of the start of El Nino is the weakening of the trade winds. The cause of such weakening is yet to be understood.   When the trade winds weaken, less warm water is pushed westward. This means the surface water in the Eastern Pacific Ocean gets warmer and there will be no upwelling of the nutrient-rich deep waters.  Upwelling brings the deep cold water to the surface. This changes the behavior of the ocean. Sea level rises when water expands because of the heat causing some flooding in the east while water level drops in the west because the water now flows eastward.

Effects of El Niño on Weather

The changes in water temperature in a vast ocean can severely affect the air pressure above it.  The warm water in ocean’s surface caused by El Nino can trigger thunderstorms. Since water moves eastward during El Niño, thunderstorms follow the same path. This explains why deserts in Peru experiences heavy rainfall while tropical countries like Indonesia experiences drought. The extreme rise and fall in the ocean level can cause droughts and flooding. Bush fires in Australia are severe during El Nino.  Because of the change in the air pressure in this part of the world, it changes the weather patterns in nearby regions.  However, such changes have ripple effects and the weather changes trickles to the rest of the world.  

Economic and Health Impact

El Niño causes extreme weather disturbance so the welfare of the people in the affected area is at risk. Different diseases spread on dry and wet weather.  On the economic aspect, farmers and fisher folks are severely affected since crops and fish supply can be scarce. Food production takes a hit.


Scientists have developed statistical techniques to predict El Niño by studying the conditions in the Pacific Ocean. Buoys are deployed to collect data on the conditions of the ocean and atmosphere. Using modern computer equipment, monitoring and predicting El Niño have improved.