This study was conducted to investigate the relationship between Northern Hemisphere blocking systems and widespread wet periods and droughts in Iran under climate change conditions. The research data included precipitation records from 43 synoptic stations, 500 hPa geopotential height data, and blocking components from 1973 to 2018. The Blocking Index (BI) was used to identify blocking events, while the ZSI (Z‑Score Index) was applied to extract wet and dry periods. Pearson correlation was also employed to examine the relationship between blocking components and drought/wet spells.The results of analyzing widespread wet and dry years in Iran showed that during the pre-global warming period(before 1995), 7 widespread wet years occurred, whereas during the global warming period (after 1995) this number decreased to 5 years. In contrast, widespread droughts increased from 16 years to 18 years. Data analysis further revealed that over the entire 46‑year period, 977 blocking cores formed, of which 41% occurred before the climate shift and 59% during the second period (global warming). In terms of intensity, more than 77% of blockings were moderate, 10.5% strong, and 12% weak. With the onset of global warming, blockings became weaker and shifted more toward land areas and higher latitudes (above 55°N); therefore, their strength decreased and their influence on Iran diminished. The migration of blockings to higher latitudes can be attributed to the increased strength of the subtropical high and reduced penetration of the polar vortex (polar low) into mid‑latitudes due to climate change. Consequently, as blocking cores shift to higher latitudes, the troughs associated with blocking systems less frequently affect Iran, leading to an increase in droughts. Correlation results between blocking components and wet/dry years indicated that under climate change conditions, the strength of blocking systems affecting Iran has decreased, resulting in reduced wet periods and increased droughts.