We investigate the temperature dependence of the spin-resolved unoccupied density of states (DOS) in ferromagnetic Co2FeAl and ferrimagnetic Mn2VAl epitaxial films on MgO(100) using x-ray magnetic circular dichroism. We observe an unexpected strong temperature dependence of the DOS beyond the change expected from the Fermi distribution function. An increase in spectral weight is observed for majority states below the Fermi energy in the case of Mn2VAl and for minority states above the Fermi energy in the case of Co2FeAl. Reduced atomic order near the interface suppresses the unexpected temperature dependence of the DOS for Mn2VAl.