Basically, during El Nino, there is low air pressure over the coast of South America and high air pressure over the north coast of Australia. La Nina is the reverse, so there is high air pressure over the coast of South America while there is low air pressure over the north coast of Australia.
During El Nino:
·Rainfall is reduced in Southeast Asia, Oceanic and India, leading to drought, crop failure and wildfires
·Heavy rain in California, Mexico and the Coasts of Peru and Ecuador often results in flooding and mudslides
·Suppression of the cold current in the east pacific devastates fish catches off the west coast of South America
·Tornados in the USA are reduced
·More cyclones in Hawaii and Polynesia but fewer in North Australia
·Southern Africa may experience drought
·East Africa may experience floods
During La Nina:
·Higher rainfall in Indonesia and the Philippines
·Lower rainfall on the west coast of South America
·Southern Africa and Southern Australia may experience floods
·Eastern Africa, California and South America may experience drought
·More hurricanes in the Caribbean and USA
Hope this has helped. Please see my revision booklet (link below) on pages 23 & 24 for the above info aided with diagrams!