The quality of groundwater in coastal aquifers is at risk in numerous regions worldwide due to seawater intrusion (SWI). The objective of this research is to analyze the condition of the Quaternary aquifer in the Sudr region of South Sinai, Egypt, and evaluate the suitability of groundwater quality for irrigation from 1996 to 2022 by utilizing hydrochemical indicators. The Western and North-Western regions exhibit high salinity levels, with a gradual decrease towards the east. The predominant water types identified in the study region include Na-Cl, Ca Mg-Cl, and Ca-Cl type. The Hydrochemical Facies Evolution Diagram (HFE-D) revealed that the area impacted by the seawater intrusion to 73.33%. The findings of spatiotemporal variation based on sodium adsorption ratio (SAR), sodium percentage (Na%), and permeability index (PI) suggest that groundwater quality for irrigation deteriorated in 2022 compared to 1996. According to the SAR data, the percentage of samples classified as excellent decreased from 71.95% in 1996 to 58.33% in 2022, with an increase in the classification of samples as good. This research contributes to the ongoing monitoring of groundwater quality in coastal aquifers, providing valuable information for decision-makers.