But the worst disaster occurs when the rains do not come at all. In the drought year of 1770, for instance, an estimated 10 million people died in the Indian state of Bengal in a famine; one million perished in Orissa in 1865-66. "The failure of the rains is the first link in the chain that leads to famine," Stephenson says. Today, however, he notes that improved storage facilities and irrigation systems have reduced the chance of famine.

On the other hand, the chance of receiving too much rain still remains a threat, particularly to people living in India's lowlands. In recent years, monsoon floods have killed up to 1,000 people a year and damaged millions of acres of crop land. Often the culprit is a flash flood, produced without warning by the monsoon's fickle and dramatic storms, which remain difficult to predict.

Despite the threat, however, Indians still celebrate the arrival of the monsoon -- fully aware that it can both sustain and end life.