Despite a late burst of heavy rain, the 2026 southwest monsoon is shaping up to be India’s driest in 11 years. Last week’s deep depression brought widespread rain to parts of east, northeast, central and north India, cutting the season’s deficit from 15% to around 12% in a span of four-five days. But the monsoon is still set to be India’s first deficient season since 2015 and among the 10 weakest monsoons since Independence.The India Meteorological Department (IMD) classifies a seasonal rainfall deficit of 10% or more as ‘deficient’, its lowest rainfall category, commonly described as a monsoon drought.The significance of this year’s rainfall deficit becomes clearer against the recent past. Five of the last seven monsoons produced either excess or above-normal rainfall. India appeared to have entered a relatively wet phase in its multi-decadal monsoon cycle, marked by fewer droughts.This year has broken that run, with El Niño playing a major role. El Niño is the periodic warming of surface waters in the central and eastern equatorial Pacific that alters atmospheric circulation around the globe. The 2026 event is developing into the strongest on record.“A clear way of identifying if El Niño has affected the monsoon is by checking whether the monsoon wind circulation has weakened,” says Roxy Mathew Koll, climate scientist at the Indian Institute of Tropical Meteorology. “This year, there was a marked weakening of these winds, which was evident right from monsoon’s onset.”The monsoon reached Kerala on June 4, just three days after the normal date, and initially advanced rapidly. By June 8, it covered much of southern India; by June 12, the northeast and much of eastern India were under monsoon winds. Then it stalled for nearly two weeks, reaching northwest India only in the first week of July.With monsoon winds weak even where the system had arrived, June ended with a countrywide rainfall deficit of more than 35%, the highest in 12 years.
Bay of Bengal lows on a high
The weakness persisted through the following months, but another feature of the monsoon changed: low-pressure systems (LPS) began repeatedly forming over the Bay of Bengal and moving inland, transporting moisture and producing heavy rain.There were no such systems in June, but four in July, six in August and three in September, including the deep depression that crossed the north Andhra-south Odisha coast on September 23-24. Thirteen LPS during these three months is above the normal 10-11.The impact is visible on the district rainfall map. A swathe of relatively good rainfall runs from parts of Rajasthan through Uttar Pradesh, Madhya Pradesh, Chhattisgarh, Jharkhand, Gangetic West Bengal and Odisha. This is broadly the corridor through which many of the LPS travelled.Odisha, impacted by nearly all of these systems, witnessed its wettest monsoon in 20 years. This year’s June-September rainfall of over 1,480mm is among the highest five the state has experienced since 1901.“When the monsoon is less organised, like this year, low-pressure systems play a much more dominant role,” Koll says. “Even though, on the large scale, El Niño’s effect on the monsoon was strong, these smaller weather systems were bringing in rain, even extreme rainfall. Had these systems been absent, the monsoon deficit may have been 20% or higher.”Western disturbances, moist weather systems moving into north India from the Mediterranean region, also remained unusually active, just as in recent years. Experts link this trend to climate change. At times, these WDs interacted with LPS, producing extreme rainfall, particularly in the Himalayan states.The result is a strikingly uneven monsoon. As of September 25, 43% of India’s districts had received deficient or scanty rainfall, with most of the rainfall-starved districts concentrated in four broad clusters. Each of these clusters tells a story.
East and northeast: Driest on record
The East and Northeast region — comprising the seven subdivisions of Bihar, Jharkhand, Gangetic West Bengal, North Bengal and Sikkim, Assam and Meghalaya, Arunachal Pradesh, and the other northeastern states of Nagaland, Manipur, Mizoram and Tripura — is heading for its driest monsoon since records began in 1901.As of September 27, the region had received 1,014.7mm against a normal 1,347mm, a deficit of nearly 25%. Even with the late-season rains, it will remain well below the previous record low of 1,069mm, set in 2013.The decline is not confined to this year. IMD data shows that average monsoon rainfall in the region since 2000 is about 15% lower than during 1981-2000, and 26% below the peak reached during 1941-1960.That is a substantial climatic shift, with potential implications for land use and ecology. Yet even during this exceptionally dry monsoon, parts of Assam and Nagaland suffered severe flooding. Experts have pointed to deforestation and development-related changes as factors that magnified the impact of the floods.
Bihar: Five droughts in a row
The most intense concentration of rainfall deficit in eastern India lies across Bihar and adjoining areas of eastern Uttar Pradesh and north Bengal.As of September 27, 31 of Bihar’s 38 districts were rainfall-deficient. The state is on course for one of its seven driest monsoons since 1901 and is experiencing its fifth consecutive monsoon drought.A 2024 CEEW (Council on Energy, Environment and Water, a public policy think tank) study of four decades of rainfall data found that during the 1982-2022 period, about 64% of Bihar’s tehsils had experienced declining rainfall in the months of June and July, while 40% recorded a fall of more than 10% across the full four-month monsoon season.
South: Driest in 24 years
The largest rainfall-deficit zone stretches from southern Madhya Pradesh, Vidarbha and Madhya Maharashtra to Kerala and Tamil Nadu.South India has a rainfall deficit exceeding 23%, making this its driest southwest monsoon since 2002. The district-level picture is starker: 88 of the region’s 147 districts, or 60%, had received deficient or scanty rainfall by September 27.Rayalaseema in Andhra Pradesh has been particularly badly affected, with a deficit of 38%.
West Rajasthan: A rare desert drought
West Rajasthan, climatologically the country’s driest subdivision, has recorded a rare 31% rainfall deficit. It is the subdivision’s first deficient monsoon in eight years and its lowest seasonal rainfall since 2009.The contrast with recent decades is striking. In the 17 monsoons since 2009, including 2026, west Rajasthan has averaged 25% above-normal rainfall. It recorded only two deficient seasons, alongside seven excess and two large-excess monsoons.
Punjab: Record wet to deficit
Punjab provides perhaps the sharpest year-to-year contrast. Its rainfall is currently 42% below normal, the largest subdivisional deficit in the country and the state’s worst monsoon since 2004.Just a year ago, Punjab received 621.6mm, or 41% above normal, its highest monsoon rainfall since 1988. Last year, floods and disease affected paddy yields in the state. This year, deficient rainfall could put both kharif and rabi crops under pressure while adding to the state’s already serious groundwater stress.Countrywide, the 2026 monsoon may end with a 12-13% shortfall. But more than the deficit, it is a story of a highly uneven monsoon: a weakened large-scale circulation, punctuated by bursts from smaller weather systems, with the result being islands of deluge amid large areas of drought.
