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As David point's out, it depends on what you mean. 'Empty space' contains no heat and so has no 'temperature'. But space is far from empty...
It also depends on what you mean by 'temperature'.
Temperature is really simply the amount of random motion of atoms (or molecules). The amount of 'heat' , or energy, there is, however, is very different and is also dependent on the mass of the material and other physical properties such as the specific heat. One way of putting the difference is that a thimble-full (1 ml) of boiling water has a high temperature (100 C or 373 K), but very little heat (energy). On the other hand, a 1,000,000 tonne thundercloud has a low temperature but a lot of heat (energy). To give numbers... I hope these are right... the 1 ml of 100 C water = 0.001 kg x 373 K x 4180 J = 1560 J The thundercloud at -20 C = 1,000,000,000 kg x 253 K x 4180 = 1,057,540,000,000,000 J of heat energy.
The factors that would affect a comet nucleus are the 'temperature' of the particles around it - the solar wind has a temperature of hundreds of thousands of degrees C - but is very tenuous so the effect is small as the heat is low. Also the light energy on the comet which is converted to heat is also small. But even so, we get sublimation and a tail, although the tail is basically a vacuum better than what we can make on Earth. There are probably other factors as well such as heating caused by gravitation (tidal) effects.
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