A cumulative thermal exposure monitor (10) having a housing (11) with a fluid sealed interior cavity (16) and a thermally-responsive member (20) therein formed of a shape memory material which moves an indicator (21), wherein the thermal properties of the housing, cavity, and shape memory material transition temperature range are calibrated relative to one another to function in mutual cooperation such that the thermally-responsive member gradually changes from a first shape to a second shape upon absorption of heat energy over time to closely match a thermal deterioration profile of a perishable product, and to indicate the cumulative amount of heat energy absorbed and whether, at any time, the temperature has been above a preferred storage temperature range for a period of time sufficient to cause any degree of deterioration based on a known time and temperature thermal deterioration profile of the perishable product.