The east coast of the United States is affected mainly by the Gulf Stream current, which brings warm water from the tropics into higher latitudes. The warm current flows north along the coast towards Maine, before veering northeast out toward England. Because warmer water evaporates faster, putting more moisture into the air, the current serves to increase the humidity of the air along the coast. This moisture occasionally gets sucked into storm systems and rained (or snowed) out over the mid- Atlantic states and New England. Similarly, because water temperature changes much more slowly than air temperature, when a cold air mass moves toward the coast from from Canada, the coastal areas will stay much warmer than farther inland. Thus, the warm ocean current tends to moderate the temperatures along the coast.
