Monsoon Calendar 2020  

#GS2 #Monsoons 

The Indian Meteorological Department has changed the dates of normal onset of monsoon across several parts of India, mainly for central and northwest India.  

What has changed?  

  • While the existing dates were based on rainfall records taken during 1901-1940, IMD now depends on data collected during 1961-2019 for forecasting the new monsoon onset dates and on data during 1971-2019 for the withdrawal dates.  
  • While monsoon onset date remains unchanged, on June 1 in Kerala, it has been delayed by three to seven days in Maharashtra, Gujarat, Madhya Pradesh, Chhattisgarh, Telangana, Andhra Pradesh, Odisha, Jharkhand, Bihar and parts of Uttar Pradesh.  
  • Over extreme northwest India, monsoon arrival data has been advanced to July 8 from July 15. There are, however, appreciable changes in the monsoon withdrawal dates.  
  • Monsoon will now withdraw from northwest India 14 days later. Yet, the final withdrawal date would remain unchanged, on October 15.  


  • The major trigger for the revision of dates were the changes in the monsoon behaviour observed by IMD during the past many years, especially due to global warming.  
  • For instance, it has been observed for quite some time now that the movement of monsoon winds, after the initial onset over southern India, becomes sluggish over central India.  
  • IMD in 2018 formed a committee to assess such observations, check if they were statistically significant and suggest changes for the onset and withdrawal of monsoon dates over India. 
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