  We have studied the properties of A=54 and A=64 isobars at temperatures T
\leq 2 MeV via Monte Carlo shell model calculations with two different residual
interactions. In accord with empirical indications, we find that the symmetry
energy coefficient, b_{sym}, is independent of temperature to within 0.6 MeV
for T \leq 1 MeV. This is in contrast to a recent suggestion of a 2.5 MeV
increase of b_{sym} for this temperature, which would have significantly
altered the supernova explosion scenario.
