Major cities in Washington

Bellingham Everett Kennewick Tacoma Seattle Spokane Vancouver Yakima Olympia Geography of Washington (state) (Washington (state))

Washington is the northwesternmost state of thecontiguous United States. It bordersIdaho to the east, bounded mostly by the meridian running north from the confluence of theSnake River andClearwater River (about 117°02'23" west), except for the southernmost section where the border follows the Snake River. Oregon is to the south, with the Columbia River forming the western part and the 46th parallel forming the eastern part of the Oregon–Washington border. During Washington's partition from Oregon, the original plan for the border followed the Columbia River east until the confluence with the Snake river, and then would have followed the Snake River east; this was changed to keepWalla Walla's fertile farmland in Washington.

To the west of Washington lies the Pacific Ocean.^[1] Its northern border lies mostly along the49th parallel, and then via marine boundaries through theStrait of Georgia,Haro Strait, andStrait of Juan de Fuca, with theCanadian province ofBritish Columbia to the north.^[2]

Washington is part of a region known as thePacific Northwest, a term which always refers to at least Washington and Oregon, and may or may not include some or all the following, depending on the user's intent: Idaho, westernMontana,northern California, British Columbia, andAlaska.

The high mountains of theCascade Range run north–south, bisecting the state. In addition toWestern Washington andEastern Washington, residents call the two parts of the state the "Westside" and the "Eastside", "Wet side" and "Dry side", or "Timberland" and "Wheatland", the latter pair more commonly in the names of region-specific businesses and institutions. These terms reflect the geography, climate, and industry of the land on both sides of the Cascades.

Major volcanoes in Washington

Mount Baker Glacier Peak Mount Rainier Mount St. Helens Mount Adams Geography of Washington (state) (Washington (state))

From theCascade Mountains westward,Western Washington has a mostlyMediterranean climate, with mild temperatures and wet winters, autumns and springs, and relatively dry summers. The Cascade Range has severalvolcanoes, which reach altitudes significantly higher than the rest of the mountains. From north to south, these major volcanoes areMount Baker,Glacier Peak,Mount Rainier,Mount St. Helens, andMount Adams. All are active volcanoes.^[3]

Mount Rainier—the tallest mountain in the state—^[4] is 50 miles (80 km) south of the city of Seattle, from which it is prominently visible. TheU.S. Geological Survey considers 14,411-foot-tall (4,392 m) Mount Rainier the most dangerous volcano in the Cascade Range, due to its proximity to theSeattle metropolitan area, and most dangerous in the continental U.S. according to theDecade Volcanoes list.^[5] It is also covered with moreglacial ice than any other peak in the contiguous 48 states.^[6]

Western Washington also is home of theOlympic Mountains, far west on theOlympic Peninsula, which support dense forests of conifers and areas oftemperate rainforest. These deep forests, such as theHoh Rainforest, are among the only rainforests in the continental United States.^[7] While Western Washington does not always experience a high amount of rainfall as measured in total inches of rain per year, it does consistently have more rainy days per year than most other places in the country.^[8]

Eastern Washington—the part of the state east of the Cascades—has a relatively dry climate, in distinct contrast to the west side. It includes large areas of semiaridsteppe and a few truly ariddeserts in therain shadow of the Cascades; the Hanford reservation receives an average annual precipitation of 6 to 7 inches (150 to 180 mm). Despite the limited amount of rainfall,agriculture is an extremely important business throughout much of Eastern Washington, as the soil is highly productive andirrigation, aided by dams along the Columbia River, is fairly widespread.^[9] The spread of population in Eastern Washington is dominated by access to water, especially rivers. The main cities are all located alongside rivers or lakes; most of them are named after the river or lake they adjoin.

Farther east, the climate becomes less arid, with annual rainfall increasing as one goes east to 21.2 inches (540 mm) in Pullman, near the Washington–Idaho border.^[10] TheOkanogan Highlands and the ruggedKettle River Range andSelkirk Mountains cover much of the state's northeastern quadrant. ThePalouse southeast region of Washington was grassland that has been mostly converted into farmland, and extends to theBlue Mountains.^[11]

Major factors determining Washington's climate include the large semi-permanenthigh pressure andlow pressure systems of the north Pacific Ocean, the continental air masses of North America, and the Olympic and Cascade mountains. In the spring and summer, a high-pressureanticyclone system dominates the north Pacific Ocean, causing air to spiral out in a clockwise fashion. For Washington, this meansprevailing winds from the northwest bring relatively cool air and a predictablydry season.^{[13][failed verification]}

In the autumn and winter, a low-pressurecyclone system takes over in the north Pacific Ocean. The air spiraling inward in a counter-clockwise fashion causes Washington's prevailing winds to come from the southwest, and bring relatively warm and moist air masses and a predictablywet season. The term "Pineapple Express" is used colloquially to describeatmospheric river events, where repeated storm systems are directed by this persistent cyclone from tropical and near-tropical Pacific regions into the Pacific Northwest.^[14]

Despite Western Washington's marine climate similar to many coastal cities of Europe, there are exceptions such as the "Big Snow" events of 1880, 1881, 1893, and 1916,^[15][16] and the "deep freeze" winters of 1883–1884, 1915–1916, 1949–1950, and 1955–1956, among others.^[17] During these events, Western Washington experienced up to 6 feet (1.8 m) of snow, sub-zero (−18 °C) temperatures, three months with snow on the ground, and lakes and rivers frozen over for weeks.^[16] Seattle's lowest officially recorded temperature is 0 °F (−18 °C) set on January 31, 1950, but low-altitude areas approximately three hours away from Seattle have recorded lows as cold as −48 °F (−44 °C).^[18]

The Southern Oscillation greatly influences weather during the cold season. During the El Niño phase, the jet stream enters the U.S. farther south through California, therefore late fall and winter are drier than normal with less snowpack. The La Niña phase reinforces the jet stream through the Pacific Northwest, causing Washington to have more rain and snow than average.^[19]

In 2006, the Climate Impacts Group at theUniversity of Washington published-The Impacts of Climate change in Washington's Economy, a preliminary assessment of the risks and opportunities presented given the possibility of a rise in global temperatures and their effects on Washington state.^[20]

Rainfall in Washington varies dramatically going from east to west. The Olympic Peninsula's western side receives as much as 160 inches (4,100 mm) of precipitation annually, making it the wettest area of the 48 conterminous states and atemperate rainforest. Weeks may pass without a clear day. The western slopes of the Cascade Range receive some of the heaviest annual snowfall (in some places more than 200 inches or 5,100 millimeters water equivalent) in the country. In the rain shadow area east of the Cascades, the annual precipitation is only 6 inches (150 mm). Precipitation then increases again eastward toward the Rocky Mountains (about 120 miles (190 km) east of the Idaho border).

The Olympic mountains and Cascades compound this climatic pattern by causingorographic lift of the air masses blown inland from the Pacific Ocean, resulting in the windward side of the mountains receiving high levels of precipitation and the leeward side receiving low levels. This occurs most dramatically around the Olympic Mountains and the Cascade Range. In both cases, the windward slopes facing southwest receive high precipitation and mild, cool temperatures. While the Puget Sound lowlands are known for clouds and rain in the winter, the western slopes of the Cascades receive larger amounts of precipitation, often falling as snow at higher elevations.^[21]Mount Baker, near the state's northern border, is one of the snowiest places in the world. In 1999, it set the world record for snowfall in a single season—1,140 inches (95 ft; 29 m).^[22]

East of the Cascades, a large region experiences strong rain shadow effects. Semi-arid conditions occur in much of Eastern Washington with the strongest rain shadow effects at the relatively low elevations of the centralColumbia Plateau—especially the region just east of the Columbia River from about the Snake River to theOkanagan Highland. Thus, instead of rain forests, much of Eastern Washington is covered with drygrassland,shrub-steppe, anddunes.

The average annual temperature ranges from 51 °F (11 °C) on the Pacific coast to 40 °F (4 °C) in the northeast. The lowest temperature recorded in the state was −48 °F (−44 °C) inWinthrop andMazama. The highest recorded temperature in the state was 120 °F (49 °C) atHanford on June 29, 2021.^[23][24] Both records were set east of the Cascades. Western Washington is known for its mild climate, considerable fog, frequent cloud cover, long-lasting drizzles in the winter and warm, temperate summers. The eastern region, which does not benefit from the general moderating effect of the Pacific Ocean, occasionally experiences extreme climate. Arctic cold fronts in the winter and heat waves in the summer are not uncommon. In the Western region, temperatures have reached as high as 118 °F (48 °C) inMaple Valley^[25] during theJune 2021 heat wave, which was reported to be a 1000-year weather event and broke several records in the Pacific Northwest.^[26][27] In Western Washington, they have also gone as low as −6 °F (−21 °C) inLongview.^[28]

This article needs to beupdated. The reason given is: Some of this data is more than five years old; parts are more than 10 years old. Please help update this article to reflect recent events or newly available information.(November 2024)

Forests cover about half the state's land area, mostly west of the northern Cascades. Approximately two-thirds of Washington's forested area is publicly owned, including 64 percent of federal land.^[46] Common trees and plants in the region arecamassia, Douglas fir, hemlock,penstemon, ponderosa pine,western red cedar, and many species of ferns.^[47] The state's various areas of wilderness offer sanctuary, with substantially large populations of shorebirds and marine mammals. The Pacific shore surrounding theSan Juan Islands is heavily inhabited bykiller, gray, and humpback whales.^[48]

In Eastern Washington, the flora is vastly different.Tumbleweeds andsagebrush dominate the landscape throughout large parts of the countryside.Russian olives and other trees are common alongside riverbanks; however, apart from the riversides, large swaths of Eastern Washington have no naturally existing trees at all (though many trees have been planted and are irrigated by people, of course). A wider variety of flora can be found in both theBlue Mountains and the eastern sides of the Cascades.

Mammals native to the state include thebat,black bear,bobcat,cougar,coyote,deer,elk,gray wolf,hare,moose,mountain beaver,muskrat,opossum,pocket gopher,rabbit,raccoon,river otter,skunk, andtree squirrel.^[49] Because of the wide range of geography, the State of Washington is home to several different ecoregions, which allow for a varied range of bird species. This range includes raptors, shorebirds, woodland birds, grassland birds, ducks, and others.^[50] There have also been a large number of species introduced to Washington, dating back to the early 18th century, including horses and burros.^[51] Thechannel catfish,lamprey, andsturgeon are among the 400 knownfreshwater fishes.^[52][53] Along with the Cascades frog, there are several forms of snakes that define the most prominentreptiles and amphibians.^[54][55] Coastal bays and islands are often inhabited by plentiful amounts of shellfish and whales. There are five species ofsalmon that ascend the Western Washington area, from streams to spawn.^[48]

Washington has a variety ofNational Park Service units. Among these are theAlta Lake State Park,Lake Roosevelt National Recreation Area,San Juan Islands National Wildlife Refuge, as well as three national parks—theOlympic National Park,North Cascades National Park, andMount Rainier National Park.^[56] The three national parks were established between 1899 and 1968. Almost 95 percent (876,517 acres, 354,714 hectares, 3,547.14 square kilometers) of Olympic National Park's area has been designated as wilderness under theNational Wilderness Preservation System.^[57] Additionally, there are 143state parks and 9national forests, run by theWashington State Park System and theUnited States Forest Service.^[58] TheOkanogan National Forest is the largest national forest on theWest Coast, encompassing 1,499,023 acres (606,633 ha). It is managed together as the Okanogan–Wenatchee National Forest, encompassing a considerably larger area of around 3,239,404 acres (1,310,940 ha).^[59]

There are 39 counties within the state, and 281 incorporated municipalities which are divided into cities and towns.^[60] The majority of the state's population lives within Western Washington, in the Seattle metropolitan area; the city of Seattle is the principal city of the metropolitan area, and Western Washington, with a 2020 census population of 737,015.^[61]

• Geography of Idaho
• Mount St Helens
• Cascadia (region)

• Geography of Washington (state)

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