A memory device having a cross point array of memory cells includes a temperature sensor and a reference memory cell. The temperature sensor senses the temperature of the memory device and data from the temperature sensor and the reference memory cell are used to update write currents used to program the array of memory cells. A method of calibrating the memory device involves detecting a temperature of the memory device, determining whether the temperature of the memory device has changed by a threshold value, and updating write current values if the temperature of the memory device changes by the threshold value. The write current values can be updated by data from the reference memory cell, or from write current values stored in a lookup table.