In spin-transfer torque random access memory (STT-RAM), the temperature fluctuations can significantly affect the characteristics of both electrical and magnetic devices. In this paper, we analyze their temperature dependence and investigate the impacts of temperature fluctuations on read and write operations. For the regular STT-RAM design working under 300 to 375 K, the sense margin in read operation can degrade about 25% and the write speed reduces around 20%. Furthermore, heating the MTJ to its Curie temperature can dramatically reduce the switching time to subnanosecond. And the design feasibility and implication are discussed in the paper.