A little less than half the surface of Mars has pressures above the triple point of water, so wherever the temperatures dip above 0C, maybe a few hours a day in

A little less than half the surface of Mars has pressures above the triple point of water, so wherever the temperatures dip above 0C, maybe a few hours a day in the equatorial regions, liquid water can exist. Deeper craters closer to the equator or seasonally in the northern lowlands or the southern Hellas or Argyre region.