When I first arrived in Delhi in early November, it was hazy with a kind of smokey, misty, polluted atmosphere. It was fine and dry, mind, but as you can see by the photo's of Connaught Place, when I arrived back in March everything was much clearer. Delhi also suffers from bad fog during December and January. In fact when I flew back to delhi after travelling to Calcutta and Orissa, my flight was delayed because of it.
The summer months- May to July, can be very hot and dry. July and August see the Moonsoon rains set in and cool down things a bit, however, this brings with it much humidity.
The best months to visit Delhi are November to March. Though January is quite chilly- and temperatures can go down as low as 1 degree cel on some days.
Delhi may not exactly conjure up visions of winter. There is however, a period that lasts anything between two to four weeks between end december and the first half of january, when the temperatures take a nosedive.
Flights are often delayed, and visibility is poor for much of the time.
The days temperatures in celsius, range between 15 degrees maximum and 3 degrees minimum.