Calculation of Junction Temperature
Try to check the Thermal Resistance Junction to Ambient  (K/W)
for istance for 1N4007 is 100 K/W, considering a voltage drop of 1V and a current of 0.1A
we will have a 0.1W therefore the junction temperature will be 10K higher than ambient.
the formula is Temperaturejunction=ThResistance*Power+Ambient temperature.
During thermal stress you could see if any offset or gain of the circuit is changing. Also if you have some hysteresis effect.