By taking measurements of background microwave radiation, scientists have been able to establish that the average temperature of the universe is just over 2.7 degrees Kelvin. This means that the average temperature of space is just below negative 450 degrees Fahrenheit.
The universe has been expanding and cooling since its formation during the Big Bang. In 1990, scientists began to make use of the Cosmic Background Explorer, known as the COBE satellite, in order to measure more accurately the microwave spectrum of background radiation. Current scientific theory as well as observable data place the average temperature of the universe at just a few degrees above absolute zero, as reported by the University of California, Los Angeles (UCLA) Division of Astronomy and Astrophysics.