Statistics relating to the date of onset of the southwest monsoon over Kerala for the 100-year period 1891-1990 reveal that the mean and median dates of onset for south Kerala are 31 May and 1 June, with a standard deviation of 8.5 days. Declaring the date of monsoon onset is not a straightforward matter. However, rainfall pattern, uppper air circulation features and INSAT cloud pictures are useful guides, and these indicate that the onset date in 1990 esd 17-18 May. During 1891-1990 there have been onlyy 12 years in which the date of onset over Kerala has been on or before 18 May.

A research paper by Gowariker have used multiple and power regression involving 15 independent variables for long range forecasting of monsoon rainfall in India. They have also argued that, when most of the independent variables are 'favourable' almost invariably the monsoon rainfall is normal. In this note we formalize this approach using a parsimonious logistic regression model. The probability of a normal rainfall can be assessed in most cases using only five of the 15 variables.