Dhanesh,

There are a lot of unknows in your question. What is the material of the coil? Is it a high resistance heater material or just normal copper coil? . Depending on the material the maximum current that can be supplied to the coil also varies. Which in turn  decides the maximum possible temperatures (Depending on heat loss factors suggested by James Garry. ) Geometry of the coil also plays a role in distribution of the heat flux around the coil. 

Dhanesh,

The coil generates heat in a conductive material at a certain rate. How quickly heat is lost from that material will dictate the maximum temperature.

If this is in air (not vacuum) then convection from the heated object will be the main heat loss mechanism, presuming that the object is suspended in some way to minimize conduction.

And what current are you pushing through the coil?

(coil winding geometry also will dictate the rate of heating)

Dhanesh,

There are a lot of unknows in your question. What is the material of the coil? Is it a high resistance heater material or just normal copper coil? . Depending on the material the maximum current that can be supplied to the coil also varies. Which in turn  decides the maximum possible temperatures (Depending on heat loss factors suggested by James Garry. ) Geometry of the coil also plays a role in distribution of the heat flux around the coil. 

Dhanesh, I see 2 possible questions: 1. How hot does the primary coil get?, and/or, 2. How hot does the secondary get (in an induction heating sense)?  In 1. heat is transferred from the coil to the ambient environment, in 2. energy is transferred from the primary coil to the secondary conductor, often not an actual coil.  Can you clarify your question?

The coil is made of copper and its shape is different from conventional coil type, its a flat coil.

Kindly see the link given below. It give you more clarity about the work.

https://www.youtube.com/watch?v=mVv0AfaGdNo

There are two ways to get your answer.

1) Define all parameters for the system. Coil dimensions, CSA, material characteristics, system frequency, current, inductive load, radiation heat transfer from the heated object, ambient air temperature, air flow etc. Then you can calculate thermal losses, eddy currents, radiation from the coil, convective cooling data etc.

OR

2) Build the system and measure the temperature with a thermocouple

Option 2) will be much quicker and accurate and easy to provide data for different operating conditions.