A comparison of the Medieval fjord hydrography and climate regime of the main Norse settlements in Greenland demonstrates important differences in the timing of sea-ice expansion and storminess when comparing the Western and Eastern Settlement regions. The Western Settlement, as well as the northern hunting grounds around Disko Bugt, had already experienced major climate deterioration in the first decades after AD 1200. This regime shift in West Greenland included an expansion of fjord and sea ice (“West Ice”) in coastal waters as well as a drastic atmospheric cooling and an increase in storminess, mainly in the summer season. In contrast, environmental conditions in the Eastern Settlement deteriorated notably later, i.e., around AD 1400. At that time, ice conditions became much more severe, whereas the previously prevailing strong wind activity decreased, which was coeval with a general decrease in aeolian activity in West Greenland, eastern Canada, and NW Iceland. Summer blockage of the fjord entrance by thick, multi-year sea ice (“Storisen”) is a specific feature of the Eastern Settlement area, whereas in the Western Settlement region, the West Ice would have threatened Norse sailing in late winter. We may thus conclude that by shortly after AD 1200 living conditions in the Western Settlement had already became less attractive due to adverse effects of the early, regional climate deterioration. Since then, the Western Settlement was probably increasingly dependent on supplies from the Eastern Settlement, where milder climate conditions continued to prevail for another century. Increased summer blockage of the Eastern Settlement fjords by the Storisen beginning around AD 1400 would have imposed serious limitations to sailing and pasture productivity in coastal areas and is suggested to have played a crucial role in the final demise of the Eastern Settlement a few decades later.