  We consider a quantum field which is in a Hartle-Hawking state propagating in
a general spherically symmetric black hole space-time. We make use of uniform
approximations to the radial equation to calculate the components of the stress
tensor, renormalized using the Hadamard form of the Green's function, on the
horizons of this space-time. We then specialize these results to the case of
the `lukewarm' Reissner-Nordstrom-de Sitter black hole and derive some
conditions on the stress tensor for the regularity of the Hartle-Hawking state.
