The ability to measure temperature in shock wave experiments has been a long-standing scientific challenge complicated by the short timescales involved (<1 microsecond) and the presence of nonthermal or external light sources that pollute measured radiances using optical pyrometry methods. In the current work, we present the first experimental data on cerium metal designed to measure the temperature on-Hugoniot from the low-pressure α phase well into the high-pressure liquid phase. Radiance data obtained in this work were used to determine the Hugoniot curves for solid (α-Ce) and liquid cerium by measuring the longitudinal stress and temperature simultaneously in the shocked state. These data were used to estimate the temperature for incipient shock melting and complete melting, and to further constrain a multiphase equation of state developed to describe the dynamic response of cerium at high pressures.