The level of pollution and the spread of harmful substances in the lower atmospheric layer are significantly affected by the meteorological conditions. This article has included an analysis of cases of adverse weather conditions formation (AWC) (conditions that contributed to the accumulation of pollutants in the air) for the period 2009-2013 and were determined by the total number of days with AWC for each year. Relevant is the fact that the highest number of days with AWC was recorded in 2010 and weather сonditions unfavorable for pollutants dispersion are formed in all seasons, but the highest frequency of the days with AWC were in summer period of years 2009, 2012 and 2013, the spring of 2010, and the autumn of 2011. According to multiannual data, the highest level of air pollution in Chisinau, Balti, Tiraspol, Bender and Rîbniţa were reported in summer and spring. For the improvement of the quality of forecasts on the level of atmospheric air pollution, it is necessary to determine the frequency of number of days with AWC in each month and each decade of the same month for the period of 2009-2013. The highest frequency of the number of days with AWC has been attested in the third decade of April.