 Current Martian surface temperatures vary from lows of about − 87 ° C ( − 125 ° F ) during polar winter to highs of up to − 5 ° C ( 23 ° F ) in summer . The wide range is due to the rarefied atmosphere , which cannot store much solar heat , and the low thermal inertia of the soil . Early in its history , a denser atmosphere may have permitted the formation of an ocean on Mars . 
