Mysore is a all the year tourist destination with pleasant weather mostly all 365 days in a year.
All the seasons like summer, winter andrian are moderate.
Its almost between 20 to 36 degrees celcius throughout the year.
Rain doesnt pour the whole day even in rainy seasons.
Winter is hjust moderate and you will enjoy your stay in Mysore.
Summer usually the temperature ranges from 30 to 35 degrees celcius.
Even if you land in mysore as tourist without any specific clothing, nothing to worry and you can almost manage it.