A memory device includes at least one reference cell and multiple memory cells. A method of operating the memory device may include detecting a temperature of the memory device and controlling a level of a first read signal applied to the at least one reference cell in accordance with a result of the detecting of the temperature. The method may also include comparing a first sensing value sensed by applying the first read signal to the at least one reference cell with a second sensing value sensed by applying a second read signal to a selected memory cell among the multiple memory cells.