Description

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Context

The recent La Niña event in tropical Pacific has officially ended according to NOAA March 2025 update with ENSO-neutral conditions now prevailing impacting global climate variability & seasonal forecast reliability.

Key Highlights

Aspect	Details
Event	End of La Niña & onset of ENSO-neutral conditions in March 2025
Agency	NOAA (National Oceanic & Atmospheric Administration, USA)
Previous Phase	A short, mild La Niña phase from late 2024 to early 2025
Current Phase	ENSO neutral sea surface temperatures (SSTs) & atmospheric indicators no longer meet La Niña thresholds
SST Measurement	Niño 3.4 region SST ~ -0.01°C (much warmer than La Niña threshold of -0.5°C)
Ocean Indicators	Warm water spread westward across eastern Pacific Subsurface cold water shrank
Atmospheric Indicators	Trade winds still strong but lack of cold SSTs ends La Niña classification
Projection (2025)	>50% chance ENSO-neutral continues through August–October; ~43% chance it lasts into early winter
Spring Predictability Barrier	Forecast confidence drops during spring due to natural atmospheric variability
Historical Record	Recent La Niña may not qualify for historical inclusion (didn't meet 5 overlapping 3-month criteria)

ENSO Phases Comparison Table

Parameter	El Niño	La Niña	ENSO-Neutral
SST Anomaly (Niño 3.4)	≥ +0.5°C above normal	≤ –0.5°C below normal	Between –0.5°C & +0.5°C
Trade Winds	Weakened or reversed	Strengthened	Near-normal
Walker Circulation	Weakened (eastward shift)	Strengthened (westward shift)	Balanced
Rainfall in Pacific	Increased in east-central Pacific, dry in west	Enhanced in western Pacific, dry in east	Typical seasonal variability
Effect on Indian Monsoon	Suppressed monsoon (weak rainfall)	Strengthened monsoon (good rainfall)	Uncertain & variable
Impact on South America	Flooding in Peru, drought in Amazon	Drought in Peru, floods in Australia	Normal seasonal variation
Global Influence	Warming events globally	Cooling events globally	No significant global anomaly
Duration	9–12 months	9–12 months	Transitional (can last months)

Impact on Indian Monsoon

Parameter	El Niño Impact	La Niña Impact	ENSO-Neutral Impact
Monsoon Onset	Delayed	Early or on time	Normal or slightly delayed
Total Rainfall	Deficit (~10–20% below normal)	Surplus (~5–15% above normal)	Near-normal but unpredictable
Intra-seasonal Variability	Higher dry spells	Better distribution	Unstable, harder to forecast
Cyclone Activity (Arabian/Bay)	Suppressed in Bay of Bengal	Enhanced in Bay & Arabian Sea	Variable
Temperature in India	Warmer summer & drier soil	Cooler summer, better soil moisture	Near-normal but unpredictable
Agriculture Impact	Reduced kharif yields, food inflation	Boost in crop output, better sowing	Depends on local patterns
Reservoir Levels	Low inflow	High inflow	Balanced or region-specific variability
Policy Implication	Need for drought planning, import support	Fertilizer demand, irrigation stable	Uncertainty in contingency planning

For more information, please refer to IAS GYAN

Sources:

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PRACTICE QUESTION

Q. While La Niña & El Niño offer climatic signals unpredictability of ENSO neutral phases complicates policy response. Analyze how ENSO neutral conditions affect Indian climate resilience strategies.