Here's why:

* Average Temperature: Uranus has an average temperature of -224°C (-371°F).

* Distance from the Sun: Being the seventh planet from the sun, it receives significantly less sunlight than the inner planets.

* Axial Tilt: Uranus has a very unusual axial tilt, almost lying on its side. This means its poles receive more sunlight than its equator for extended periods, leading to extreme temperature variations.

While Neptune is further from the sun, Uranus' unique axial tilt and atmospheric composition make it the colder planet overall.