I have no precise info about it but I think that it depends of the room temperature but without a fan is could be something around the 60-70 °C and with a fan sucking the heath from it it could be a bit lower as 45 to 60 °C Blowing with a fan to it may lower the temperature to it, but again it depends also on the room temperature and the environment. The best temperature is I think between the 40 and 50 °C