La Niña was expected to form by July 2024 but it has yet to emerge, leading to predictions of a delayed onset in late 2024 or early 2025.

About La Niña

• Definition: La Niña occurs when sea surface temperatures in the East-Central Tropical Pacific are at least 0.5°C cooler than the 30-year average.
• ENSO Phases: It is the counterpart to El Niño, which involves warmer-than-usual Pacific waters. Both significantly influence global weather and climate.
• Triple Dip La Niña: The decade began with three consecutive La Niña events (2020–2022), followed by an El Niño in 2023, an occurrence linked to climate variability.

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Pattern and Prediction of La Niña

• Historical Pattern: La Niña typically develops during the monsoon or pre-monsoon period and rarely forms between October and December. 
  • Since 1950, this late formation has occurred only twice.
• Forecast:Current forecasts from the U.S. National Oceanic and Atmospheric Administration (NOAA) estimate a 57% chance of La Niña forming in 2024, and if it does, it will likely be weak.
• Required Condition: The Oceanic Niño Index (ONI), a key metric for declaring ENSO phases, is currently around –0.3°C, below the threshold of –0.5°C required to confirm La Niña. 
  • Five consecutive months of such values are needed for official classification.

Global Impact of La Nina

• Hurricanes and Storms: La Niña intensifies hurricanes over the Atlantic Ocean, increasing their frequency and severity.
  • The 2020 hurricane season recorded 30 named storms, breaking records.
• Droughts: La Niña often triggers droughts in parts of Africa, South America, and the southwestern U.S.
  • The 2010–2011 La Niña caused severe droughts in the Horn of Africa, leading to widespread food shortages.
• ENSO and Climate Change: Rising global temperatures are expected to amplify the frequency and intensity of La Niña events, potentially worsening extreme weather globally.

Impact of La Nina on India

• Monsoon and Rainfall: La Niña years bring robust monsoons, as seen in 2020, 2021, and 2022, supporting agriculture and water resource replenishment.
  • Above-normal rainfall during the 2021 monsoon boosted crop yields.
• Colder Winters in North India: Harsher winters occur due to disrupted atmospheric circulation.
  • The 2020–2022 La Niña period recorded colder-than-usual nights in northern regions.
• Relief from Extreme Summers: Persistent La Niña into 2025 could temper heat, reducing the severity of heatwaves.
  • The El Niño of 2023 caused record-breaking heat; La Niña could mitigate this trend.
• Air Quality Dynamics: Lower Planetary Boundary Layer Height (PBLH) traps pollutants near the surface, potentially worsening air quality during La Niña winters.
  • Stronger winds reduce pollution levels, but colder temperatures increase biomass burning, worsening air pollution.

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El Niño vs. La Niña

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