Low-Pressure Systems Reshape 2026 Monsoon
Why in News?
- Down To Earth published a cover story on 16 October 2026 analysing how low-pressure systems shaped the 2026 southwest monsoon, using India Meteorological Department rainfall data.
- June had no low-pressure system and all-India rainfall was 35 per cent below normal. July had low-pressure systems active on 24 of 31 days.
- August and September saw 26 and 27 low-pressure system days against normals of 17 and 16.
- The analysis finds that low-pressure system activity has become more persistent than the long-term normal.
Key Terminologies
- Low-Pressure System
- A weather system with lower air pressure than its surroundings that draws in moist air and brings rain. During the monsoon, many form over the Bay of Bengal and move inland.
- Depression
- A stronger stage of a low-pressure system, with higher wind speeds and heavier rain. A deep depression is stronger still.
- Homogeneous Regions
- The four zones the India Meteorological Department uses to compare rainfall: northwest India, central India, south peninsula, and east and northeast India.
- Normal Rainfall
- The long-term average rainfall for a place or period, against which the India Meteorological Department reports surplus or deficit.
Key Issues
- A Month-by-Month Swing: June rainfall was 35 per cent below normal with no low-pressure system. July ended 1 per cent above normal, as central India rose to 33 per cent above normal, according to the analysis.
- Persistent Systems: In July, four low-pressure systems were active for 24 of 31 days, which is 10 more than the long-term July average. August had 26 days against 17, and September 27 against 16.
- Uneven Regions: In September, northwest India got 17 per cent more rain than normal, while east and northeast India were 25 per cent short and the south 27 per cent short.
- Extreme Local Impact: The first system of July formed on 2 July, became a depression and caused extreme rain, flash floods and landslides in Himachal Pradesh and Uttarakhand. A deep depression over the Bay of Bengal on 22 September brought heavy rain to Uttar Pradesh, where 56 people died in rain-related incidents.
- Season Totals: All-India rainfall was 16.3 per cent below normal in August and 8 per cent below in September, so strong systems did not guarantee a normal season.
Key Implications
Positive/Pros/Merits
- Better Understanding: Counting low-pressure system days gives a clear way to explain why rainfall can be above normal in one region and far below in another.
- Central India Gains: Central India moved from 50 per cent below normal in June to 33 per cent above normal in July.
- Evidence for Planning: Data on persistent systems can help agencies prepare flood and landslide plans in hill and plain states.
- Forecast Scope: Improved models under Mission Mausam aim to track such systems with radars, computing and artificial intelligence.
Negative/Cons/Demerits
- Floods With Deficits: More system days did not prevent deficits, since August rainfall was 16.3 per cent below normal and the east, northeast and south were short in September.
- Uneven Rain Risk: Heavy bursts over a few regions can cause floods and landslides even in a deficit year.
- Intensification Concern: The analysis suggests a larger share of systems is intensifying into depressions or deep depressions, though the excerpt gives no numbers.
- Limited Detail: The page reviewed is an excerpt, so the full dataset and trend figures could not be checked.
Key Initiatives
- India Meteorological Department Data: The department publishes rainfall data for India and its four homogeneous regions, which the analysis uses to compare months and regions.
- Mission Mausam, 2024: The Union Cabinet approved Rs 2,000 crore for 2024 to 2026 for weather and climate science, led by the India Meteorological Department, the National Centre for Medium-Range Weather Forecasting and the Indian Institute of Tropical Meteorology.
- Mission Mausam Infrastructure: It plans 50 Doppler Weather Radars, 60 radiosonde and radio wind stations and 100 disdrometers, besides urban testbeds and ocean research stations.
- Artificial Intelligence in Forecasting: The mission uses artificial intelligence and machine learning models to improve short-term forecasts and long-term climate projections.
The India Meteorological Department monitors low-pressure systems and issues rainfall data and warnings, while Mission Mausam aims to improve forecasts through radars, supercomputing and artificial intelligence. The Down To Earth excerpt reviewed does not discuss any government response to the trend in low-pressure systems.
Director's Perspective
Way Forward
- Issue district-level warnings when a low-pressure system is expected to stall over a region, since persistence raises flood and landslide risk.
- Use low-pressure system tracks in reservoir and river management, so that releases are planned before heavy rain.
- Strengthen hill-slope monitoring and early warning in Himachal Pradesh and Uttarakhand, where extreme rain triggered landslides.
- Publish season-end low-pressure system statistics with rainfall data, so that researchers can test trends across decades.
The 2026 monsoon shows that how rain falls matters as much as how much. Frequent low-pressure systems can produce deadly local extremes even when the season total is below normal, and the pattern seems to be growing more persistent. The limit is that the evidence reviewed is a media analysis excerpt. In a Mains answer, explain the Bay of Bengal systems and regional variation, then conclude that forecasting and local preparedness must focus on intensity and distribution, not just totals.
GS Relevance
Frequently Asked Questions
What is a low-pressure system in the monsoon?
A low-pressure system is a weather system with lower air pressure than its surroundings, which draws in moist air and brings rain. During the monsoon many form over the Bay of Bengal and move inland, and stronger stages are called depressions and deep depressions.
What did the 2026 monsoon analysis find about low-pressure systems?
The Down To Earth analysis of India Meteorological Department data found that low-pressure systems were active on 24 days in July, 26 in August and 27 in September 2026, well above normal. It also found that these systems have become more persistent than the long-term normal.
How did the 2026 monsoon rainfall vary by month?
All-India rainfall was 35 per cent below normal in June, 1 per cent above normal in July, 16.3 per cent below normal in August and 8 per cent below normal in September 2026, according to the Down To Earth analysis of India Meteorological Department data.
PYQ Practice — Statement Analysis
1 Low-pressure systems of the monsoon commonly form over the Bay of Bengal and move inland.
They can intensify into depressions and deep depressions.
2 The India Meteorological Department compares rainfall across five homogeneous regions.
It uses four: northwest, central, south peninsula, and east and northeast India.
3 A deficit season total means that no region can receive extreme rainfall.
Heavy bursts can cause floods and landslides even in a deficit year.