High Temperature RFID Tags range from 200°C to 400°C and most are designed to be mounted on metal (MOM).  Generally speaking, FR4 & ABS packaging survives 200°C while Ceramic packages survive 230°C.  Nylon packages survive 300°C and one particular Tag of metal packaging also capable of being welded for attachment is capable of 400°C.  No High Temperature RFID Tag can be read while at maximum temperature thus several seconds of cooling may be necessary.