[en] We describe a simple technique for estimating kinetic temperatures (T/sub kin/) from intensities of adjacent rotational transitions of symmetric top molecules. The method relies on two assumptions: (1) that the metastable levels (lowest energy level in each K ladder) are thermalized; and (2) that the excitation temperature connecting the upper level of the observed transition to the losest level in the K ladder is the same for both adjacent transitions. The method is applied to observations of the J = 5--4 and J = 6--5 transitions of CH₃CCH obtained at 1' intervals along a NS-EW cross centered on Orion KL, Sgr B2, and Dr 21. Surprisingly, T/sub kin/ inferred from CH₃CCH is almost constant across the faces of Sgr B2 and DR 21; T/sub kin/ may peak at the center in Orion, but no strong case can be made for this from our data. Toward Sgr B2 and DR 21 we find mean temperatures of 49 K and 30 K, respectively; toward Orion we find 48 K at the center and an average temperature over all positions of approx.35 K