There is not actually a single uniform temperature for all of outer space; it tends to be warmer (at least in a relative sense) in areas that are closer to stars or planets. On average, though, the temperature is only about 3 Kelvin, which is about -270 degrees Celsius. It is extremely cold in outer space, so we humans would not last long floating around in the far reaches of space (even if we could breathe there, which we can’t).