One of Mr. Jinnah's quotes I remember is "Karachi clouds have no water in them". I personally believe that we should be lucky that it rarely rains in Karachi (and there have been years without any rain at all).

On June 30, 1977, the city was paralyzed after a 9 inch rainfall. Nursery Market was submerged in water for many days, and after the water receded, the marks left on the walls of shops showed that the water had been so high that short people (and children) would have drowned in it.

Today we had four inches of rain, and we can expect that no one will turn up to work tomorrow at our office tomorrow (it's Saturday, a day on which the staff goes home at three, unless there is a very heavy work-load, which doesn't happen often).

The only time we had heavy rains in winter was on February 18, 1979. I remember the date because the rain had dissolved the entire stock of salt in my open-air salt works located in the coastal area of Karachi. 

In engineering college, we learnt why (in the entire subcontinent), the only airport in the region had been constructed in Karachi. It was because this was the only city that had a stable climate all the year round and the British needed such a place between the two world wars. For many years after independence, all international flights used to depart from Karachi only (even people living in erstwhile East Pakistan had to come to Karachi to go to foreign countries). Now of course, every major city in Pakistan has a large airport, with flights to foreign countries departing from Karachi, Lahore, Quetta, Peshawer, and even Sialkot (where the airport was built by private entrepreneurs).