Pakistan experience a general deficiency of rainfall. Although the country is in the monsoon region, it is arid, except for the southern slopes of the Himalayas and sub-mountainous tract which have a rainfall from 5 inches to 35 inches. Balochistan is the driest part of the country with an average rainfall of 8 inches.
The Punjab has an average annual rainfall of about 15 to 20 inches, Sindh 6 to 10 inches and Khyber Pakhtunkhwa7 to 9 inches. The South-West monsoon reaches Pakistan towards the beginning of July and established itself by the middle of the month.
The strength of the monsoon current increase from June to July; it then remains steady, and starts retreating towards the end of August, though occasionally it continues to be active even in September when some of the highest floods of the Indus Basin have been recorded.