The suitability of temperature as a parameter to determine strain failure mode in press forming is examined by thermographic evaluation of the forming limit diagram (FLD). The work reported in the present paper forms part of a research programme to develop condition monitoring technology for press forming, the highlights of which are discussed. Experimental methodologies are described. The inability to use temperature to distinguish between the left and right hand sides of the FLD is reported. A strong correlation between major strain and fracture temperature is also observed. From this, it is concluded that it may be possible to perform condition monitoring of press forming, by a technique termed 'thermal line analysis'.