Experiments were made of the time-average temperature and thermal-fluctuation profiles occurring during pool boiling from a horizontal copper surface with water, Freon-113, and methanol as fluids. These profiles show a similar nature when scaled by a length called the sublayer thickness, δ. These results show that the correlations for sublayer thickness with other system parameters can be divided into two distinct regimes. For low heat fluxes, one relation correlates the data of all three fluids. At higher heat fluxes, the correlating requires different constants for the different fluids in a manner similar to boiling heat-transfer correlations.