We report on the temperature and coverage dependence of the reflection high energy electron diffraction lineshape during homoepitaxy of Fe/Fe(1 0 0). In the submonolayer regime, with increasing temperature, a continuous evolution from well resolved diffuse satellites to a broad diffraction structure is observed. These satellites are interpreted in terms of coherent scattering between neighboring islands. We show that the diffraction line obeys a scaling behavior with temperature, reflecting the evolution of the island distribution evidenced by scanning tunneling microscopy. We also show that in the kinematic approximation, an intensity transfer between Bragg and diffuse contributions can explain the linewidth oscillations observed during layer by layer growth in metal epitaxy.