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Benchmarks of Normal Monsoon Behaviour and Possible Shifts

2. Benchmarks of Normal Monsoon Behaviour and Possible Shifts


i) South-west monsoon over different parts of the country sets in at different times between May and September.  Its  normal  onset  period  over  Kerala  is around  29th  May and  by June  1st  week,  the  northern  limit  of  monsoon  passes over  Karnataka,  Manipur  and  Tripura.  By the second week of June, the limit passes through Mumbai, Kolkata and covers the states of Assam and Arunachal Pradesh.


ii) The  onset  over  the  north-western  parts  of  India  is  around  last  week  of June  to  the  first  week  of  July  and  covers  the  entire  country  within  about  30 days. Similarly, monsoon withdrawal starts from the second week of September over  the  northern  parts  and  around  15th   October,  the  south-west  monsoon conditions cease to operate.


iii) Breaks  in  monsoon  situations  result  from  the  change  in  the  track  of tropical  depressions  from  Bay  of  Bengal  and  their  number  in  a  given  month give rise to dry spells over certain sub-divisions in any given year. It happened in 2009 due to cyclone called Aila.


 The four broad scenarios for which one has to plan for contingency are:

I.          Delayed onset

Maximum of three weeks from normal date for the given   region.  This happened in North-west India in 2002 and North West and North East India in 2009.

II.   Early onset and sudden breaks.


This scenario happened in some parts of the country in 2009.

III. Early withdrawal of monsoon


By last week of August and causes stress during maturity of crops.

IV. Delayed withdrawal or extended monsoon.

May    damage     matured    crops    at     the harvesting time.

V.   Various permutations and combinations of above  four scenario.

Complexities of management increases.



















                                                                                                                                        Ministry of Agriculture, GOI.






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Please note that this is the opinion of the author and is Not Certified by ICAR or any of its authorised agents.