Why does western Ireland receive more rain than eastern Ireland?

Western Ireland receives significantly more rainfall than eastern Ireland primarily because it is the first point of contact for moisture-laden weather systems arriving from the Atlantic Ocean.1

The country’s climate is classified as western maritime, characterized by prevailing westerly winds that carry warm, moist air toward the island. As these air masses move eastward, they frequently bring clouds and precipitation. Western areas are directly exposed to these incoming systems, resulting in annual precipitation that can exceed 100 inches (2,533 mm).123

In contrast, by the time these weather systems reach the eastern part of the country, much of their moisture has already been released, leading to significantly lower annual rainfall, which averages about 30 inches (760 mm) in the east. This gradient is further influenced by the island's topography, as hills and mountains can accentuate rainfall in western regions.13