We report the detection of the (J,K) = (1,1), (2,2), and (3,3) inversion lines of ammonia (NH3) towards the south–western molecular lobe in M82. The relative intensities of the ammonia lines are characterized by a rotational temperature of Trot = 29 ± 5K which implies an average kinetic temperature of Tkin ≈ 60K. A Gaussian decomposition of the observed spectra indicates increasing kinetic temp...