Comprehensive temperature-dependent optical modeling of perovskite solar cells (PSCs) and modules is essential to accurately predict their energy yield and quantify their energy losses under real-world operating conditions, where devices are subject to different irradiance spectra and intensities as well as operating temperatures. These models require the accurate determination of the temperature-dependent optical constants of perovskites. Here, we report on these data, empirically determined via spectroscopic ellipsometry, for triple-cation perovskites with band gaps ranging between 1.58 and 1.77 eV at temperatures between 25 and 75 °C. Using this data set, we develop a simple empirical model to obtain the temperature-dependent optical constants of perovskites of an arbitrary band gap. We validate our empirical model by comparing the measured temperature-dependent short-circuit current densities and external quantum efficiency data of single-junction PSCs with simulated results using the modeled optical constants.