"Type II-P supernovae (SNe) are marked by the long plateau in their optical light
curves. The plateau is believed to be the result of a recombination wave that
propagated into the outflowing hydrogen envelope of the star, releasing the energy that was deposited in it by the shock wave. The early stages of the evolution, when the SN envelope is fully ionized, were well modeled in several analytic works. However, a description of the SN envelope in the later stages of the evolution is still lacking. In this work we analytically investigate the transition from a fully ionized envelope, to a partially recombined one, and its effects on the temperature and bolometric luminosity. We assume a simple, but adequate, hydrodynamic profile of the ejecta, and follow the diffusion of photons as they propagate through the SN envelope. Following the ionization fraction and the coupling between radiation and gas, we derive the evolution of the temperature and bolometric luminosity with time. We find that once the recombination front reaches the inner parts of the outflow, it sets the observed temperature to be nearly constant, and slows the decline of the luminosity (or even leads to a modest re-brightening). We find the power law decline of the temperature and luminosity and compare our findings to recent observational results."