This paper addresses the problem of predicting the maximum electron density in the ionosphere related to the critical frequency (foF2) of the ionospheric F2 layer. The spatial dependence and temporal evolution of foF2 values define the behaviour of an HF propagation channel. This paper proposes the simplified forecasting model to predict electron density profile one day ahead. The prediction method is based on analysis of time series of measured foF2 profile. The data obtained from GIRO network database were used in investigation. Statistics of foF2 daily profile recorded by neighbouring ionosondes during 12 years were built. Comparisons between the observed and predicted vertical ionograms are presented to show the appropriateness of the proposed technique.