Computing a Probability Distribution for the Start of the Rains from a Markov Chain Model for Precipitation

The start of the rains is defined to be the first day, or two-day rain spell, in which greater than a specified total amount of rain occurs. A method of calculating the probability distribution of the start of the rains from a Markov chain model of the daily precipitation is given. The application of this method is illustrated with data from Samaru, Nigeria.