The accuracy of force fields is a key to the successful prediction of the thermodynamic properties of materials. In simulations of organic molecules over large temperature ranges, atomistic force fields that are parametrized at, or near, ambient temperatures are found to systematically underestimate the intermolecular dispersion interactions at elevated temperatures. Analysis of the underestimates using diatomic molecules indicates that a minor part is due to the change in molecular polarizability, while the major part is due to the reduced dielectric constant of the bulk liquid as the density decreases with increasing temperature. By establishing the dispersion parameter as a linear function of temperature, we have successfully enhanced the temperature transferability of atomistic force fields. This approach is tested on 66 molecular liquids covering four functional groups - alkane, aromatic, ether, and ketone-aldehyde - over a broad range of temperatures by calculating liquid density, heat of vaporization, isobaric heat capacity, and shear viscosity.