The above graph shows the relation between Noise Figure (in dB) to the Noise Temperature (in K). Note that the reference temperature is taken as 290 K
\(Noise\, Temperature (K) = T_{Ref} *\left ( 10^{\frac{NF(dB)}{10}}1 \right )\)
\(Noise\, Figure (dB) = 10*log10\left ( \frac{T_{Noise}(k)}{T_{Ref}(k)}+1 \right )\)
Where: 
\(NF (dB)\) = Noise Figure in dB 
\(T_{Noise}(k)\)= Noise Temperature in kelvin 
\(T_{Ref}(k)\) = Reference Temperature in kelvin 
Other Related Calculator:

Noise Factor ↔ Noise Figure Calculator