A recently developed technique retrieving the binned raindrop size distributions (DSDs) and air state parameters from ground‐based K a and W‐band radars Doppler spectra profiles is improved and applied to a typical midlatitude rain event. The retrievals are thoroughly validated against DSD observations of a 2D video disdrometer and independent X‐band observations. For this case‐study, profiles of rain rate, R , mean volume diameter and concentration parameter are retrieved, with low bias and standard deviations. In light rain (0.1 < R < 1 mm h −1 ), the radar reflectivities must be calibrated with a collocated disdrometer which introduces random errors due to sampling mismatch between the two instruments. The best performances are obtained in moderate rain (1 < R < 20 mm h −1 ) where the retrieval is providing self‐consistent estimates of the absolute calibration and of the attenuation caused by antenna or radome wetness for both radars.