A method of correcting reflectivity measurements performed by a radar, such as a weather radar, includes a reflectivity measurement being associated with a resolution volume. The method includes acquiring the reflectivity measurement Zm corresponding to the current resolution volume, estimating the attenuation kc introduced by the cloud droplets, said estimating being carried out by using an average vertical profile of the cloud liquid water content, estimating the attenuation kg,O2 introduced by dioxygen, estimating the attenuation kg,H2O introduced by the water vapor, determining the total specific attenuation k of the non-detectable components taking into account the attenuation kc, the attenuation kg,O2 and the attenuation kg,H2O estimated in the preceding steps, and correcting the measured reflectivity taking into account the estimated total specific attenuation k. The method may be implemented by an onboard weather radar.