...Let’s begin by examining this year’s monsoon rainfall month by month. Monsoon season in India begins in June. This year, the month saw no low-pressure system (LPS) activity, and rainfall was 35 per cent below normal across the country; central India received 50 per cent less rain than usual. The monsoon recovered in July, particularly because of LPS activity. The first LPS formed on July 2, which later intensified into a depression and produced rainfall along the east-to-northwest corridor stretching as far as up to Himachal Pradesh and Uttarakhand. These Himalayan states recorded extreme rainfall, flash floods and landslides. Another LPS, formed towards the end of July, also strengthened into a deep depression. In total, four LPS formed in July and they remained active for 24 of the 31 days in the month. That was 10 days more than the long-term average of LPS days for July, defined as the number of days on which an LPS is active somewhere over India that month.
The high level of LPS activity, concentrated over the monsoon core region in central India, pushed rainfall there to 33 per cent above normal in July (from a 50 per cent deficit in June), and thereby lifted all-India rainfall to 1 per cent above normal (from a 35 per cent deficit a month ago). By contrast, northwest India, where rainfall is less influenced by LPS events, recorded a deficit of 4 per cent. East and Northeast India and the southern peninsula also recorded deficits of 29 per cent and 25 per cent, respectively.
The link was stark in eastern India, where rainfall was deficient in states that the LPS did not traverse. Bihar received 42 per cent less rain than normal by July 31, while neighbouring Jharkhand had a deficit of 29 per cent. Odisha, through which the LPS travelled, recorded 34 per cent more rainfall than normal.
August showed a similar pattern. That month, India as a whole received 16.3 per cent less rain than normal. All the four homogeneous regions of the country, as categorised by IMD for rainfall analysis, recorded deficits, but northwest India and central India had the smallest (at 9.5 per cent and 16.2 per cent, respectively). By comparison, northeast India and the southern peninsula recorded 16.9 and 27.1 per cent deficits. This regional contrast coincided with unusually high LPS activity: there were 26 LPS days in August against a normal of 17. During these days, six LPS formed and moved from Odisha towards northwestern India, concentrating rainfall along this corridor and particularly over the Indo-Gangetic plains. Two of the systems intensified into depressions.
All-India rainfall in September was 8 per cent below normal; deficits were large in eastern and northeastern India (at 25 per cent) and in the southern peninsula (at 27 per cent). Northwest India, by contrast, received 17 per cent more rain than normal, while central India recorded an excess of 3 per cent. This regional contrast was largely driven by LPS activity, which in northwest interacted with unseasonal western disturbances already prevailing over the region. September recorded 27 LPS days, compared with a long-term average of 16. Four LPS were active during this period. One of them intensified into a deep depression over the Bay of Bengal on September 22, and moved from Andhra Pradesh across central and northwest India. It produced exceptionally heavy rain in Uttar Pradesh, where 56 people died in rain-related incidents. Even the little bit of rain in northeast India was due to a deep depression formed near Myanmar towards the end of the month.
Low-pressure days on the rise
Down To Earth conducted further analysis to understand if monsoon rainfall in recent years has become more dependent on the formation and progression of these convective storm systems. The analysis suggested two important shifts. One, the number of LPS days during the southwest monsoon season has been higher than the long-term normal, which suggests that LPS activity has become more persistent. Two, a larger share of these systems appears to be intensifying into depressions or deep …
This exclusive analysis was originally published as part of the cover story "Intimate takeover" in the October 16-31, 2026 print edition of Down To Earth
For Complete Access, Subscribe Now