Why in News? 

• The Indian Meteorological Department expects La Niña to develop by late 2024 or early 2025, after initial predictions for July were not realized. 

What is La Niña? 

• La Niña, meaning "The Little Girl," is part of the El Niño Southern Oscillation (ENSO) cycle, influencing global climate. ENSO has three phases: 
• El Niño (Warm Phase): Weak trade winds cause warmer waters in the eastern Pacific. 
• La Niña (Cool Phase): Stronger trade winds push cooler waters to the eastern Pacific. 
• Neutral Phase: No significant temperature difference between the eastern and western Pacific.

Impact on Weather 

• La Niña typically enhances monsoon rainfall in India, though its effect on the 2024 monsoon season is limited. 
• If La Niña starts by September or October, it may influence the northeast monsoon (Oct-Dec), affecting Tamil Nadu, Kerala, and coastal regions. 
• La Niña years may see more intense cyclones and colder winters. 

Conclusion 

• La Niña’s impact includes changing rainfall patterns, increased cyclone frequency, and colder winters. Understanding these phases helps predict global weather changes.