‘Western disturbances lingering in India till monsoon due to climate change, causing extreme rainfall in Himalayas ’
The continued presence of western disturbances (WD) during active southwest monsoon (SWM) conditions in 2025 is contributing to extreme rainfall, flash floods and landslides in the Western Himalayan region.
These extra tropical cyclonic circulations may be forming closer to India than the usual western disturbances that form close to the Mediterranean region and need to be studied. On August 24, 2025, the India Meteorological Department (IMD) stated that “a western disturbance as a trough in westerly lay over north Pakistan and neighbourhood.”
The current western disturbance is the fifth for August and 15th for the entire monsoon season of 2025. Earlier, there have been five WDs in June and five in July, as per a Down To Earth (DTE) analysis based on data from the IMD. “This is indeed an unusually high number of WDs for a summer monsoon!” said Kieran Hunt, Natural Environment Research Council independent research fellow in tropical meteorology and artificial intelligence at the University of Reading, United Kingdom, to DTE. Hunt is a well known expert on WDs and their impacts on India.
DTE interacted with Hunt via email on the subject of increased WDs during the monsoon season, the possible causes and what could be done to mitigate the extreme rainfall-related disasters due to this anomaly?
Akshit Sangomla (AS): Is there an increase in western disturbances during the current monsoon season?
Kieran Hunt (KH): Certainly yes. The numbers you quote from the IMD data are far in excess of the normal values (usually 0 or 1 per month in July and August, maybe up to 2 in June).
AS: How anomalous is such an occurrence?
KH: I’m not sure, but we do know that there has been a rapid increase in these ‘monsoonal WDs’ in the last few decades, and so events like this that were rare in the past are effectively becoming the new normal.
AS: Do you think WDs have had an influence on the various extreme rainfall events in the mountains during the monsoon season that have led to landslides and flash floods?
KH: Very likely that at least some of these would not have happened without WDs. (Though without going through case by case, impossible to put a number on it!)
AS: What could be the possible reasons for this increase in WDs?
KH: Historically, the subtropical jet — the upper level winds that typically bring WDs to the subcontinent — retreats northward (away from India) in April or May. Climate change has delayed this retreat, such that many more WDs are starting to arrive during the monsoon. This is still an active area of research.
AS: What could be done to improve our forecasts and preparations of such events?
KH: Several things. These events are really tricky to forecast because they combine two things that our weather models are typically not good at: deep convection and interactions with orography. Increasing model resolution, which India has been doing, is one solution. But for advance warning, we also need ensemble forecasting. This allows us to scope the range of possible events well in advance, and plan accordingly.