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The variation of synoptic systems impacting Iran's precipitation climatology can have significant climatic consequences. Among the cyclones contributing to the occasionally widespread precipitation in Iran are the coincident Mediterranean-Red Sea cyclones (CMRSC). This research aims to elucidate the long-term associated with the frequency and intensity of CMRSC by examining geopotential height (GH) and geopotential height gradient (GHG), along with CMRSC patterns, as influential factors on Iran's precipitation climatology. To achieve this, 4-daily GH data at 1000 hPa from the European Centre for Medium-Range Weather Forecasts (ECMWF), ERA-Interim, spanning from 1979 through 2018, were utilized. Throughout this period, a total of 97 CMRSC events accompanied precipitation in Iran. Methodologically, the non-parametric Chi-square test, alongside the Standard Normal Homogeneity Test (SNHT), were employed to assess variations in the cyclones' frequency and strength. The Chi-square non-parametric statistic was harnessed to discern trends in GH and GHG, while linear regression was applied to ascertain long-term trends. The findings indicate that the number of CMRSC did not display statistically significant changes over the study period when comparing successive decades and two successive halves of the time series. Notwithstanding, a more detailed examination of shorter timescales, particularly towards the end of the study period, disclosed statistically significant changes in two- and four-year averages. Additionally, the increase in GH at the formation site of Mediterranean cyclones and the decrease in GHG likely contributed to reduced atmospheric instability and precipitation in the affected regions. A pronounced GHG jump in the Mediterranean Sea in 1996 divided the time series into two distinguishable periods. The results demonstrate an upward trend in both periods; however, the second period exhibited a more gradual increase compared to the preceding period. [ABSTRACT FROM AUTHOR]