The temperature (T) dependence of magnetic moments in SrB6 is studied through spin-polarized band calculations for a supercell of Sr27B156 containing a B6 vacancy. The magnetic moment decays rather quickly with T despite the fact that only electronic Fermi–Dirac effects are included. This result and the T dependence of moments near an La impurity can hardly explain the reports of a very high Curie temperature in hexaborides, but suggest that the magnetism is caused by some other type of impurity.