The first signs of an El-Nino are1. Rise in surface pressure over the Indian Ocean, Indonesia, and Australia.2. Fall in air pressure over Tahiti and the rest of the central and Eastern Pacific Ocean.3. Warm air rises near Peru, causing rain in the Northern Peruvian deserts.4. Warm water spreads from the west Pacific and the Indian Ocean to the East Pacific.5. It takes the rain with it, causing extensive drought in the Western Pacific and rainfall in the normally dry Eastern Pacific.

El Niño and La Niña are climate patterns in the Pacific Ocean that can affect weather worldwide.
During normal conditions in the Pacific ocean, trade winds blow west along the equator, taking warm water from South America towards Asia. To replace that warm water, cold water rises from the depths — a process called upwelling.

El Niño and La Niña are two opposing climate patterns that break these normal conditions. Scientists call these phenomena the El Niño-Southern Oscillation (ENSO) cycle.