The measurements with a CIMEL CE 318 sun photometer near St. Petersburg within the AERONET international monitoring network are analyzed. Typical regional aerosol optical parameters (aerosol optical depth, Angstrom exponent, and single scattering albedo) and their variations are determined. Certain regularities in variations in the aerosol parameters over the northwest region of the Russian Federation are revealed. The study is supplemented by the joint analysis of data from the nearby AERONET observation sites in Finland and Estonia, satellite measurements, and MERRA reanalysis data.