How cold is the Moon?
Stand on the Moon at noon and the ground is hot enough to boil water. Wait two weeks for night to fall in the same spot and it drops far colder than anywhere on Earth. One kind of crater is colder still.
5 min read
The Moon does not have one temperature. It has two, and they are about 290 degrees apart, in the same spot, a couple of weeks apart.
A day that lasts a month
The Moon spins slowly. One full day, sunrise to sunrise, takes about 29.5 Earth days. That means the sunlit side bakes in full daylight for roughly two Earth weeks straight, then sits in darkness for two more.
By the time "noon" finally arrives, the ground has had two straight weeks to heat up, and it shows: NASA and other sources put the surface as high as 120°C, hot enough to boil water. Two weeks later, that same patch of ground has had two weeks of night to cool, and it falls to about -171°C.
Why there is no in between
On Earth, air does two jobs at once. It carries heat from the sunny side of the planet to the night side, and it holds some of that heat near the ground after dark, like a blanket. The Moon has next to no atmosphere, so neither job gets done.
Whatever heat lands on a patch of lunar ground has to leave the same way it arrived, by radiating straight up into space, with nothing to slow it down. So the surface swings between an oven and a freezer, and never settles in between.
Colder than anywhere on Earth
Near the Moon's poles, the Sun never climbs high in the sky. Inside some craters there, sunlight grazes the rim but never reaches the floor. Those floors have sat in permanent shadow for billions of years.
NASA's Lunar Reconnaissance Orbiter measured one, Hermite crater, at -248°C. That is the coldest temperature ever recorded anywhere in the solar system, colder than the surface of Pluto.
Why the cold spots matter
A crater floor that never warms up is also a crater floor that never lets ice evaporate. Scientists think water ice has been sitting frozen in these shadows for billions of years, and that ice could one day become drinking water, breathable air, or rocket fuel for a Moon base. It is a large part of why NASA's Artemis landings are aimed at the south pole rather than the open plains Apollo visited.
Common questions
How cold does it get on the Moon at night?
About -171°C. The Moon has almost no atmosphere to hold heat near the surface, so once the two-week lunar night begins, the ground cools fast and keeps cooling.
How hot does the Moon get in the daytime?
Up to about 120°C in full sunlight, hot enough to boil water. The same ground swings to deep cold once night falls two Earth weeks later.
What is the coldest place on the Moon?
The floor of Hermite crater, near the north pole, where NASA measured -248°C. Sunlight never reaches it, and it is the coldest spot ever measured anywhere in the solar system.
Why does NASA care about the Moon's cold craters?
Because they are cold enough to trap water ice for billions of years without it evaporating. That ice is a major reason Artemis landings are targeting the lunar south pole.