- The monsoon is a seasonal weather phenomenon of intense rainfall between June and September, caused by moisture-laden clouds sweeping across the sub-continent from the southwest.

- The monsoon delivers most of India's rainfall and has a key impact on the economy. Only a third of India's crops grow on irrigated land and a weak monsoon can wipe out many incomes and shrink demand for farm equipment and consumer goods.

- Economic growth was cut to 4 percent in the year to March 2003 after a weak monsoon, but surged to 8.5 percent the following year thanks to stronger rains.

- Monsoon rains vary widely. The average annual rainfall is 88 cm (35 inches), but some northwestern parts get just 20 cm (8 inches) while Cherrapunji in the northeast receives an average 1,100 cm (433 inches).

- The first Indian monsoon forecast was issued in 1886. In the last 135 years, the monsoon has been "normal" 94 times -- when rainfall was either 10 per cent above or below average. Droughts, when rainfall is less than 90 percent of the average, occurred in 23 years, and rainfall was in "excess," or more than 10 percent of the average, 18 times.

- The India Meteorological Department (IMD) came in for criticism for failing to predict droughts in 2002 and 2004.