Abstract Rocket measurement data of the vertical electric fields in the mesosphere are analysed. Available data indicate that there exists a diurnal variation of the mesospheric electric fields with universal time. This variation is more pronounced at middle latitudes. The large vertical electric fields with strength exceeding ∼1 V/m are present in the lower mesosphere only about between 12:00 UT and 01:00 UT, coinciding the maximum of universal diurnal variation of a fair-weather electric field on the earth's surface (the Carnegie curve). This suggests that thunderstorm activity affects the electric field structure in the mesosphere.