Statistically optimal nearfield acoustical holography (SONAH) can be used to reconstruct 3‐D sound fields by projecting 2‐D sound pressure data measured on a small measurement aperture. When the sound pressure data are measured by using a small microphone array mounted on a high‐speed vehicle, the mean flow effects of a moving fluid medium should be considered in the SONAH procedure. Here, an improved SONAH procedure is thus proposed that includes the mean flow effects. The backward projection performance of the proposed SONAH procedure is also improved by using a wave number filter to effectively reduce subsonic noise components that are exponentially amplified during the backward projection. For the purpose of validating the proposed SONAH procedure, a monopole simulation at a fluid medium velocity of Mach = −0.6 is conducted. The sound fields reconstructed by using the proposed SONAH procedure lead to more accurate sound source locations and radiation patterns than the conventional NAH and SONAH procedures. An experiment with two loudspeakers is performed in a wind tunnel operating at Mach = −0.12. The locations and radiation patterns of the two loudspeakers can be successfully identified from the sound fields reconstructed by using the proposed SONAH procedure.