A statistical analysis is performed on the interannual variability of the spring transition date in the mesosphere/lower thermosphere (MLT) region. We have analysed daily prevailing zonal winds obtained at Obninsk (55°N, 37°E) with meteor radar for the period from 1973 to 2011. The date is defined as the day when the prevailing zonal wind preliminary filtered with the 27-point Hamming filter crosses the zero level. Significant correlations between the interannual variability of the spring date and the variability of the Northern annular mode (−0.57) and between the interannual variability of the spring date and the stratospheric polar vortex breakup date (−0.66 under the westerly quasi-biennial winds at 10hPa) witness the vertical coupling between the MLT region and stratosphere through the wave activity. A comparison with the variability of the zonal mean zonal gradient wind estimated from temperature measurements by MLS aboard the AURA satellite is provided.