One of the current problems of our contemporary time is related to the changes in the climate of local, as well as global scope. We offer an analysis of long-term time series of meteorological data from different weather stations in Bulgaria. The data collected so far contains more than 68 000 values for the period 1905 – 2022. There are close to 200 time series from 37 meteorological stations in Bulgaria. In the context of the tendency of global climate change, we made a comparison with data about region which is very different in climatic aspect. We compared the results obtained in Bulgaria with the wavelet analysis results obtained in Eastern Siberia. Observational data for Siberia are provided by RIHMI-WDC (http://meteo.ru/data). Based on data from Bulgarian meteorological stations, we detected a periodicity in long-term variations of the near-surface air temperature, cloudiness and precipitation using wavelet analysis. Results for four meteorological stations are presented. Three of them have the longest time series of yearly mean values with very short gaps. The data from Irkutsk contains monthly average values and have a similar time window with uninterrupted monitoring and correspond to our methods of analysis. The presented results show similarities regarding the periodicity of temperature, precipitation, and cloudiness between Bulgarian and Irkutsk stations. The analytic periods could be related to the influence of El Niño and the North Atlantic Oscillation (NAO). Our first results from the data analysis show the existence of periodical meteorological anomalies with period of 2-6 years. This shows that the influence of NAO, Strong El Niño and La Niña events could be of definitive role for regions of Earth’s surface with different climate.