Floods, dry spells and a 16% rain deficit: India’s monsoon is becoming harder to read
India's southwest monsoon (which began on 4 June) is running at a 16% nationwide rainfall deficit as of 27 July, even as several regions simultaneously report severe flooding.
The deficit is highly uneven: East and Northeast India and the Southern Peninsula each show around 29-30% deficits, Northwest India around 10%, and Central India only about 4% below normal.
At the district level, roughly 53% of districts recorded deficient or large-deficient rainfall, while only about 12% received excess rainfall — indicating a highly patchy monsoon rather than a uniform shortfall.
Assam has reported flooding across a dozen districts and hundreds of affected villages despite an overall regional deficit, illustrating how short, intense bursts of rain can cause flooding even in a "deficient" season; parts of Mizoram, Jammu and Kashmir, Himachal Pradesh, Gujarat and Maharashtra have also faced flood or landslide impacts.
The volatility is being linked to a combination of El Niño conditions, unusually active western disturbances during the monsoon season, and the broader effect of global warming on rainfall intensity.
Long Period Average (LPA) and IMD Rainfall Classification
Rainfall deficits and surpluses are measured against the Long Period Average, the statistical baseline IMD uses to describe whether a season's rainfall is "normal."
Key Details
- LPA is the average rainfall recorded over a specific region across a long historical period (currently the 1961-2010 base period); the all-India southwest monsoon LPA is 880.6 mm
- IMD's standard classification (percentage departure from LPA): Deficient (less than 90% of LPA), Below Normal (90-96%), Normal (96-104%), Above Normal (104-110%), Excess (more than 110%)
- A separate district/area-level classification used for spatial distribution: Large Excess (≥60% departure), Excess (20-59%), Normal (-19% to +19%), Deficient (-59% to -20%), Large Deficient (-99% to -60%)
- The southwest monsoon (June-September) contributes about 70-75% of India's annual rainfall and is critical for kharif agriculture and reservoir recharge
The reported "16% national deficit" and "53% of districts deficient" figures are both derived from this LPA-based classification system — the national aggregate can mask sharply divergent regional pictures, exactly what is being observed in 2026.
El Niño-Southern Oscillation (ENSO) and Indian Monsoon
El Niño is one of the principal global climate drivers cited for the 2026 monsoon's erratic behaviour, and its relationship with Indian rainfall is a recurring Prelims/Mains theme.
Key Details
- El Niño refers to the periodic warming of central and eastern equatorial Pacific sea-surface temperatures, part of the El Niño-Southern Oscillation (ENSO) cycle; El Niño years have historically been associated with weaker Indian summer monsoon rainfall
- The mechanism: El Niño alters the Walker Circulation and shifts convection away from the Indian Ocean/Indian subcontinent toward the central Pacific, weakening monsoon moisture flow
- The historically strong ENSO-monsoon teleconnection has weakened since the 1980s; a positive Indian Ocean Dipole (IOD) can partly offset El Niño's suppressive effect on Indian rainfall
- IMD monitors ENSO alongside the IOD, Madden-Julian Oscillation (MJO) and Eurasian snow cover as inputs to its seasonal monsoon forecasts
A high-probability "super" El Niño developing later in 2026 is cited as a factor that could further suppress rainfall in the remaining monsoon weeks, compounding the deficit already recorded in the southern and eastern parts of the country.
Western Disturbances and Their Unusual Monsoon-Season Activity
Western disturbances are typically a winter phenomenon, so their interaction with the 2026 southwest monsoon is a notable anomaly with direct relevance to disaster-management and climatology questions.
Key Details
- A western disturbance is an extratropical storm system originating in the Mediterranean/Caspian region, driven eastward by the mid-latitude westerly jet stream, picking up moisture over Iran and Afghanistan before reaching the Himalayan region
- Normally brings non-monsoonal winter and pre-monsoon precipitation (and snow) to northwest India and the western Himalayas, important for the rabi crop cycle
- When a western disturbance interacts with monsoon moisture (a monsoon-westerly "interaction" event), it can trigger unusually intense, concentrated rainfall over the Himalayan belt — a known trigger for flash floods and landslides
- Climate scientists have flagged an increase in such off-season western disturbance activity coinciding with the monsoon in recent years
The interaction of monsoon moisture with active western disturbances is being cited as a contributor to the concentrated, intense rainfall events causing flooding in Himalayan and northern states even as the national seasonal deficit remains high.
Climate Change and Monsoon Variability
The article links the current monsoon's instability directly to global warming, which is the broader static concept examiners test through current climate events.
Key Details
- Global mean surface temperature is currently estimated at about 1.4°C above pre-industrial levels, consistent with IPCC AR6 findings on accelerating warming
- Warming increases atmospheric moisture-holding capacity (per the Clausch-Clapeyron relationship, roughly 7% more moisture per 1°C of warming), which intensifies extreme rainfall in short bursts even when total seasonal rainfall is normal or deficient
- IPCC AR6 (2021-2023) projects increased frequency of both monsoon "active" bursts (heavy rain) and "break" spells (dry periods) over India under continued warming
- India's National Action Plan on Climate Change (NAPCC) and state action plans increasingly factor in monsoon variability for water-resource and disaster planning
The described pattern — sharp swings between dry spells and cloudbursts rather than steady, evenly distributed rainfall — matches the IPCC's projected signature of a warming-driven monsoon, distinguishing this year's variability from simple year-to-year natural fluctuation.
- National monsoon rainfall deficit (as of 27 July 2026): 16%, monsoon onset 4 June 2026
- Regional deficits: East and Northeast India ~30%, Southern Peninsula ~29%, Northwest India ~10%, Central India ~4%
- District-level spread: ~53% of districts deficient/large deficient; ~12% excess rainfall
- Assam: 12 flood-affected districts; over 700,000 people affected across 856 villages despite a regional deficit
- All-India southwest monsoon LPA (1961-2010 base): 880.6 mm; monsoon contributes ~70-75% of India's annual rainfall
- Probability cited for a "super" El Niño developing October-December 2026: 81%
- Active monsoon phases in 2026: 29 June-9 July and 19-24 July, with another phase expected from 28 July