We show that the tail distribution U of the explosion time for a multidimensional diffusion (and more generally, a suitable function U of the Feynman-Kac type involving the explosion time) is a viscosity solution of an associated parabolic partial differential equation (PDE), provided that the dispersion and drift coefficients of the diffusion are continuous. This generalizes a result of Karatzas and Ruf (2015), who characterize U as a classical solution of a Cauchy problem for the PDE in the one-dimensional case, under the stronger condition of local Hölder continuity on the coefficients. We also extend their result to U in the one-dimensional case by establishing the joint continuity of U . Furthermore, we show that U is dominated by any nonnegative classical supersolution of this Cauchy problem. Finally, we consider another notion of weak solvability, that of the distributional (sub/super)solution, and show that U is no greater than any nonnegative distributional supersolution of the relevant PDE.