Context: 

India Meteorological Department (IMD) has forecasted a rainy September for several parts of north India due to the expected La Nina conditions.

Background: 

La Niña has several notable effects on India, primarily due to its influence on the monsoon season and overall weather patterns.

About La Niña:

1. La Niña is a climate pattern characterized by the cooling of sea surface temperatures in the central and eastern tropical Pacific Ocean.
2. This phenomenon is part of the larger El Niño-Southern Oscillation (ENSO) cycle, which also includes El Niño (the warming phase) and a neutral phase.

Key features of La Niña:

1. Cooler Ocean Temperatures: The central and eastern Pacific Ocean experiences cooler-than-average sea surface temperatures.
2. Weather Impacts: La Niña typically brings wetter-than-normal conditions to Southeast Asia, Australia, and parts of India, while causing drier conditions in the southwestern United States and parts of South America.
3. Monsoon Influence: In India, La Niña is often associated with stronger monsoon seasons, leading to above-average rainfall.
4. Global Effects: It can influence global weather patterns, including increased hurricane activity in the Atlantic and cooler, wetter winters in the northern United States.

Effects of La Niña on India:

1. Enhanced Monsoon Rains: La Niña typically brings above-average rainfall during the monsoon season (June to September). This can be beneficial for agriculture, as it improves water availability.
2. Flooding Risks: While increased rainfall can be beneficial, it also raises the risk of flooding, particularly in low-lying areas and regions with poor drainage systems.
3. Agricultural Productivity: The increased rainfall can lead to better crop yields for rain-fed crops like rice, sugarcane, and pulses. However, excessive rain can also damage crops and lead to waterlogging.
4. Water Resources: La Niña can improve the water levels in reservoirs, rivers, and groundwater, which is crucial for irrigation and drinking water supplies.
5. Temperature Variations: La Niña can lead to cooler-than-normal temperatures in some parts of India, especially during the winter months.
6. Pest and Disease Outbreaks: The wetter conditions can create a favourable environment for pests and diseases, which can harm crops and reduce yields.