In terms of weather, in all likelihood do expect rains.
However, the place around is relatively good for a couple of days in which you can cover the places like ASI sites and the small island.
Hi, Firstly from Mumbai it will be overnight journey by direct bus (if those are running)
Buses drop you to hospate from where it's again 13 km by road (rickshaw you can get) If you drive from Mumbai irs a whol days travel so your 3day trip goes for a toss Once at Hampi you can stay at many budget stays available and cover the beauty of this place. 3 days you will cover things in a rush and mostly the asi sites you can visit. Please hire a cycle there to cover places and you can cross over to other side as well with the cycle. Please plan accordingly. As per your plan most of your time will be spend on to and fro journey only 😒 Try checking this blog for trip from Mumbai https://www.tripoto.com/karnataka/trips/hampi-reflection-of-greece-in-india-photoblog-583feaf1b89b4