  Disorder-free localization is a paradigm of strong ergodicity breaking that
has been shown to occur in global quenches of lattice gauge theories when the
system is initialized in a superposition over an extensive number of gauge
sectors. Here, we show that preparing the system in a thermal Gibbs ensemble
without any coherences between different gauge sectors also gives rise to
disorder-free localization, with temperature acting as a disorder strength. We
demonstrate our findings by calculating the quench dynamics of the imbalance of
thermal ensembles in both $\mathrm{U}(1)$ and $\mathbb{Z}_2$ lattice gauge
theories through exact diagonalization, showing greater localization with
increasing ensemble temperature. Furthermore, we show how adding terms linear
in local pseudogenerators can enhance temperature-induced disorder-free
localization due to the dynamical emergence of an enriched local symmetry. Our
work expands the realm of disorder-free localization into finite-temperature
physics, and shows counterintuitively that certain quantum nonergodic phenomena
can become more prominent at high temperature. We discuss the accessibility of
our conclusions in current quantum simulation and computing platforms.
