Let's say their is a Earth sized planet orbiting a sun like star in its habitable zone. This planet has a tilt and rotation rate similar to Earth. The planet however has an atmosphere of 0.1 bar. The planet orbits its star close enough to have an average temperature of 12 C. From what I understand the boiling point of water in a 0.1 bar atmosphere is 46 C. Would oceans of liquid water remain stable in this environment? I'd imagine air temperatures reaching above 46 C and below 0 C throughout the day.