Mars is very cold
Even on the brightest, warmest summer day, the temperature on Mars is only like our 10 degrees above zero-Farenheit, or 22 degrees below the freezing point of water.
When the sun goes down, all the heat escapes into the sky.
If you were standing on Mars, your feet may be warm, but your ears would be freezing
In winter, it is so cold that the air actually freezes out the sky, trapped in polar ice caps until spring