Many parts? Ehh? October is usually known for the October heat that sets in prior to the cooler months of November and December.
Having stayed in 4 of the host cities, I can safely say that Mumbai, Pune Hyderabad, Lucknow and Bangalore aren't affected by monsoon at this time. From friends in Delhi and Calcutta I know that the monsoon is over.
If you are considering Chennai =many parts, then perhaps your assumption might be correct, as I've never stayed there. But then again,to call it as 'monsoon for many parts of the country' seems a tad far-fetched.