The years 1965 and 1966 will be remembered in Indian history as two successive years in which the failure of the south-west monsoon had a disastrous effect on Indian economy. This article is an attempt to find out the basic causes of this large-scale deficiency in the monsoon rainfall.

The S.W. monsoon or summer monsoon is a major event in the agricultural life of India, which has been widely studied. The chief characteristic of the pressure distribution over India during the monsoon is the trough of low which extends from the the S.E. Punjab to the head of the Bay and the concomitant high pressure belt in the Indian Ocean.