Syllabus: GS-I & V: Geophysical Phenomena

Why in the News?

With the monsoon entering its withdrawal phase in September 2025, the India Meteorological Department (IMD) has confirmed that the rainfall deficit in the Northeast cannot be compensated this year. 

About Rainfall Deficit in Northeast

• The Northeastern region (Assam, Arunachal Pradesh, Meghalaya, Nagaland, Manipur, Mizoram, and Tripura) is one of India’s wettest zones, receiving ~2500 mm annual rainfall on average.
• However, in 2025, Assam, Meghalaya, and Arunachal Pradesh recorded very low rainfall compared to the seasonal average.
  • Cherrapunjee (Sohra)  Meghalaya, once the wettest place on Earth, is facing its driest-ever monsoon, with a 45% rainfall deficit this year.
  • Historically, Sohra received 24,555 mm in 1974, while nearby Mawsynram overtook it as the world’s wettest place by late 1970s, with a record 26,000 mm in 1985.
• As of mid-September 2025, the cumulative rainfall deficit for the Northeast was around 25–30% of normal.
• Long-term trend: Studies reveal Northeast has been losing annual rainfall every year over the last 42 years, reflecting the climate crisis and changing monsoon dynamics in the region.

Why the Northeast Might Experience Deficit Rainfall This Monsoon?

• Inverse Monsoon Relationship: IMD highlighted a characteristic pattern: when western India gets a good monsoon, Northeast receives less rainfall.
• Track of Low-Pressure Systems: Normally, low-pressure systems in the Bay of Bengal move northeastwards towards Bangladesh, bringing rain to Assam and adjoining states.
  • In 2025, 17 low-pressure systems formed, but they tracked westwards instead, towards Rajasthan and central India, depriving the Northeast of its usual rainfall.
• Monsoon Trough Shifts: The axis of the monsoon trough oscillated more towards central and western India this year.
• Climate Variability: Global circulation anomalies like the El Niño–La Niña transition and warming of the Indian Ocean may have influenced rainfall distribution.
  

Factors Affecting Rainfall in Northeast

• Topography: Steep hills and valleys create high spatial rainfall variability.
• Bay of Bengal Depressions: The primary source of monsoon rainfall in the Northeast.
• Western Disturbances & Mid-Latitude Troughs: Sometimes disrupt moisture inflows.
• Deforestation and Land Use Change: Affect local micro-climates and hydrology.
• Climate Change: Increasing unpredictability and extreme weather events.
  

Which Regions of India Experienced a Good Monsoon?

• Northern and Western India: Rajasthan, Gujarat, and parts of Punjab saw excess rainfall due to multiple westward-moving low-pressure systems from Bay of Bengal.
• Central India: States like Madhya Pradesh and Maharashtra also received good rains.
• Eastern India: Including West Bengal and Odisha, recorded below-normal rainfall, similar to the Northeast.
• This contrasting pattern reflects the spatial imbalance of rainfall distribution.

Why North India Will Receive a Good Monsoon in 2025?

• Frequent Low-Pressure Systems in Bay of Bengal

• • As per IMD, 17 low-pressure areas developed in the Bay of Bengal this season.
  • Instead of moving northeast, most of these systems travelled westwards, carrying moisture into central and northwestern India

• Moisture Convergence in Indo-Gangetic Plains
  • Strong monsoon winds from the Bay of Bengal and Arabian Sea converged over the Indo-Gangetic belt, ensuring sustained rainfall activity.
• Enhanced Western Disturbance Activity
  • The interaction of monsoon currents with frequent western disturbances amplified rainfall over Punjab, Haryana, Himachal Pradesh, and Uttarakhand.
• Orographic Advantage
  • The Shivalik and Himalayan foothills acted as natural barriers, forcing moist winds to rise and condense, producing heavy rainfall in Uttarakhand, Himachal Pradesh, and Jammu.
• Delayed Withdrawal of Monsoon
  • Withdrawal of monsoon from northwest India was delayed, extending rainfall activity in Rajasthan, Delhi, and adjoining regions well into late September.
• Localized Climate Variability
  • Shifts in monsoon circulation patterns this year favored northwest India more strongly than the Northeast, reflecting the see-saw nature of India’s monsoon distribution.
    

About the 10 New Advanced Radars

• IMD Director General of Meteorology, highlighted that 10 advanced radars are being installed in the region to improve prediction and early warning systems.
• Objective: Enhance rainfall monitoring and early warning in the Northeast.
• Technology: Doppler Weather Radars capable of short-term (nowcasting) and medium-range forecasting.
• Coverage: Will fill current gaps in hill states like Arunachal Pradesh and Meghalaya where forecasting is weak.
• Implementation: Tenders have been floated, and installation will be phased over 2–3 years.
• Expected Impact:
  • More accurate rainfall prediction.
  • Better flood and landslide forecasting.
  • Early alerts to communities through local languages and digital networks.
    

Way Forward

• Strengthen Forecasting: Expand radar and automatic weather station networks; integrate with satellite data.
• Watershed and Catchment Management: Reforestation and wetland rejuvenation to reduce runoff during intense spells.
• Regional Monsoon Studies: Invest in dedicated research for Northeast monsoon variability under National Monsoon Mission.
• Cross-Border Cooperation: Data-sharing with Bangladesh and Bhutan for integrated hydrological forecasting.
• Climate Resilience: Promote climate-resilient agriculture and water harvesting structures to adapt to variability.
  

Conclusion

The 2025 monsoon deficit in the Northeast underscores the regional disparities in rainfall within India’s monsoon system. While Rajasthan and western states saw excess rains, the Northeast’s dependence on Bay of Bengal systems left it vulnerable. Advanced radars, better forecasting, catchment management, and community preparedness are critical to building resilience. Long-term planning, not just short-term relief, is needed for a region that remains India’s monsoon paradox.

Mains Practice Question

1. Despite being one of the wettest regions of India, the Northeast often faces rainfall deficits during certain monsoon years. Explain the reasons behind this variability and suggest measures to strengthen forecasting and resilience in the region. (250 words / 15 marks)

The Assam Tribune