ABSTRACTWe present here an in situ technique to measure the microstructure of the temperature field in our atmosphere. It consists of an autonomous payload that computes the structure function of the temperature, along with an off‐the‐shelf meteorological sonde that gives air pressure, temperature, humidity, and wind speed. This technique, which has been intensively cross‐calibrated, gives a high spatiotemporal resolution, allowing us to achieve an optical turbulence profile C2N(h) with a better than 6 m vertical resolution. It has been designed to allow simultaneous measurements of the temperature structure function in various geometrical configurations. Its versatility, reliability, and accuracy helped us to successfully undertake many astronomical site testing campaigns, as well as offer new insights into the physics of the optical turbulence.