The crest of the Cascade Range divides Washington into two distinct climatic regions. The area west of the Cascades, which is exposed throughout the year to rain-bearing winds from the Pacific Ocean, has a temperate marine type of climate that is characterized by mild wet winters and cool summers. The Cascades prevent the moist air blowing in from the Pacific from reaching eastern Washington. The Rocky Mountains on the eastern border also represent a climatic barrier. As a result, the severe winter storms that sweep the Northern Plains States do not reach Washington. Eastern Washington is much drier than western Washington, and its summers are hotter and its winters are colder.
Average January temperatures in eastern Washington range from less than -7°C (20°F) to -1°C (30°F) and often drop down to -18°C (0°F). January averages in western areas range from less than 0°C (32°F) at the higher elevations to more than 4°C (40°F) along the Pacific Coast. July averages in the east are from 18° to 24°C (65° to 75°F). However, daytime temperatures are often above 32°C (90°F). By contrast, July averages in the west are mostly in the vicinity of 16°C (60°F). The western coast has mild temperatures throughout most of the year, with relatively few days below freezing.
The Olympic Mountains receive more precipitation than any other area in the mid-continental United States, often more than 3,600 mm (140 in) yearly, much of it snow. The Cascades receive almost as much, and more than 7,600 mm (300 in) has been known to fall on the mountain peaks in one year. Precipitation in Seattle, in the Puget Trough, averages 940 mm (37 in) per year, while the eastern slopes of the Cascade Range and much of the east receive only about 380 mm (about 15 in). In parts of the Columbia Plateau in south central Washington, an average of only about 150 mm (about 6 in) falls annually.
Because of the extreme climatic differences between eastern and western Washington, the growing season ranges from 100 days in some of the mountain areas to 280 days along parts of the Pacific shore. In eastern Washington the growing season is from 120 to 200 days. In the Puget Trough the growing season is from 160 to 240 days. "Washington" © Emmanuel BUCHOT, Encarta, Wikipedia
Photos of European countries to visit
Photos of Asian countries to visit
Photos of America