A hot wire has a limited life in high‐speed wind‐tunnel flows because it is typically subjected to large dynamic loads. As a consequence hot films and modified hot wires are frequently used for turbulence measurements in such flows. However, the fluctuation sensitivities of such probes are reduced because of various factors, leading to erroneous results. This paper described the results of tests on some sensors in both subsonic and supersonic boundary‐layer flows. A simple technique to determine dynamic calibration correction factors for the sensitivities is also presented.