REGIONS > OREGON CENTRAL COAST > COAST RANGE MOUNTAINS​

Despite its low profile, the Coast Range Mountains produce a dramatic effect on local weather

​As moisture-laden winds blow inland from the Pacific Ocean, the mountains act as a natural barrier which forces the air upward. The air cools as it rises, causing the water molecules to clump together and fall as precipitation. By the time the air clears the top of the range, much of its moisture has already fallen back to earth in the form of rain or snow. This creates a distinct rain shadow effect on the east side of the mountain range, covering a large part of the Willamette Valley and resulting in a more moderate climate.

​These conditions make the Willamette ideal for agriculture. On the west (ocean) side of the range, the increased precipitation results in numerous streams, creeks, rivers and lakes — most of which eventually feed back into the Pacific Ocean and complete the hydrologic cycle.