Climate and monthly weather forecast
Washington, USA

Washington mainly exhibits continental climate (Köppen climate classification Csb, Cfb, Dfb) in the west and semi-arid type in the east (Köppen BS, BW) of the Cascade Range. Idaho in the east, Oregon in the south, the Pacific Ocean to the west, and the Canadian province of British Columbia in the north, border the state. The climate varies substantially from west to east, spanning from oceanic, Mediterranean, and subarctic to semi-arid. The Pacific Ocean, the Olympic, and Cascade mountains chiefly influence the climate of the state.

Washington, the Evergreen State, lies at the extreme northwest of the United States, with an average elevation of 520 meters above seas level. The Cascade Range that runs north-south bisects the state into a wet western part and a dry eastern part. The topography consists of high mountains, volcanoes, dense forests, temperate rainforests, rivers, semi-arid steppe, and deserts. The rain shadow region of the Cascade Mountains receives scanty rainfall of 6" (152mm), while the windward side sees abundant snowfall that reaches 200" (5080mm) annually. The temperate rainforests lie on the western side of the Olympic Peninsula, where the annual rainfall crosses a massive 160" (4064mm).

The best time to visit Washington is from June to September during summer and early fall seasons. The skies are clear, the days are sunny, and the conditions are pleasant. The temperatures range from warm to moderately hot across the state. Camping, fishing, and hiking in the higher mountain lakes and streams region begins after the melting of snow in late spring and lasts until fall. The exciting whale watching season lasts from April to October. Summer is the peak tourist season, but May and September have pleasant weather and fewer crowds.

The worst time to visit Washington is from December to February in the cold season. Winters are severely cold in the majority of the state. The skies are gray, the conditions are chilly, and the atmosphere is wet. Moist air from the ocean and the formation of the low-pressure center during fall and winter starts the wet season by the beginning of October. Rainfall is heavy in the high and windward side of the mountains. Snowfall is massive in the highlands and ample in the rest of the state except for the coastal regions. Strong winds with speeds of 50mph (80.5km/h) add to the chill factor. Winter sports attract many tourists to mountain resorts with activities like skiing, snowboarding, and snowshoeing.

Spring in Washington is a time of renewal and change, especially as temperatures begin to climb from the colder winter months. In the western part of the state, the average high temperatures in March and April hover between 50°F (10°C) and 60°F (15.6°C), making it a more comfortable time for outdoor activities. Eastern Washington is generally warmer, and the temperatures can reach the high 60s°F (around 68°F (20°C)) in April. Rainfall during spring is moderate, with western Washington receiving more moisture than the east. The season is marked by blooming flowers and the return of migratory birds, offering ample opportunities for bird watching and photography.

Summers are starkly different between western and eastern Washington. In the west, temperatures are fresh and relatively dry, peaking at an average high of 78°F (25.6°C) in July. On the other hand, eastern Washington can get scorching, with temperatures soaring from 105°F (40.6°C) to 115°F (46.1°C). Thunderstorms are more common in the mountains and can occur for seven to fifteen days. Precipitation during these months is generally low, particularly in the eastern regions where it can dip to as low as 7" (178mm) annually.

Autumn brings a shift in temperatures and weather patterns. In western Washington, the climate starts to cool, with high temperatures in October usually in the 60s°F (around 60.1°F (15.6°C) to 68°F (20°C)). Eastern Washington also experiences a decline in temperatures but remains relatively warmer. Fog is common during late summer and early fall, especially in the lowlands. Rainfall starts to pick up across the state, although it is light to moderate and can last for extended periods. The season provides a scenic backdrop of falling leaves and a palette of autumn colors, especially in the forests and mountainous regions.

Winters in Washington are generally mild but wet in the west, with average low temperatures dropping to 23°F (-5°C) in January. Eastern Washington, however, faces frigid conditions, as nighttime temperatures regularly dip from -10°F (-23.3°C) to -20°F (-28.9°C). Wind speeds can reach 40 to 50mph (80.5km/h) (64.37 to 50mph (80.5km/h)) during the winter, with occasional Chinook winds that can rapidly increase temperatures. Snowfall varies significantly, from 10" (254mm) in areas like Puget Sound to 75" (1905mm) in the east. Some mountain peaks maintain snow caps throughout the summer, notably Mount Rainier and Mount Baker, which record some of the highest snowfall and snow depths in the United States.

January stands out as one of the coldest months in Washington, particularly in eastern regions where the chill is more pronounced. In western Washington, average low temperatures drop to 23°F (-5°C). Eastern Washington experiences more extreme cold, with nighttime temperatures commonly ranging from -10°F (-23.3°C) to -20°F (-28.9°C). Weather in January »

February in Washington often marks a gradual transition from the severe cold of January to milder conditions. In western parts of the state, average low temperatures inch up slightly but remain cold, hovering near 25°F (-3.9°C). Weather in February »

March ushers in early signs of spring in Washington, especially in its western half. In cities along the Puget Sound, such as Seattle and Tacoma, average low temperatures rise to approximately 32°F (0°C). Eastern Washington starts to shed its extreme winter cold, with nighttime temperatures generally falling between 0°F (-17.8°C) and 10°F (-12.2°C). Weather in March »

April represents a turning point in Washington's climate, bringing a palpable shift towards spring across the state. Western cities, including Bellevue and Everett, see average low temperatures climb to a more comfortable 38°F (3.3°C). Weather in April »

May in Washington serves as a prelude to summer, particularly in western cities like Seattle and Olympia where average low temperatures reach about 45°F (7.2°C). Eastern Washington, including areas like Wenatchee and Pullman, follows suit, with nighttime temperatures generally between 30°F (-1.1°C) and 40°F (4.4°C). Cloud cover starts to dissipate more noticeably in May, paving the way for an increasing number of sunny days. Weather in May »

June signifies the onset of summer in Washington, with conditions becoming consistently warm and increasingly dry. Western Washington, encompassing cities like Bellingham and Tacoma, experiences average low temperatures of about 50°F (10°C). Weather in June »

July stands as the pinnacle of summer in Washington, offering the warmest and driest conditions of the year. Western cities such as Seattle and Olympia experience average low temperatures of approximately 55°F (12.8°C). In contrast, the eastern half of the state, featuring cities like Yakima and Pasco, sees nighttime lows ranging from 50°F (10°C) to 60°F (15.6°C). Sunshine dominates the weather pattern in July. Weather in July »

August sustains the summer warmth but begins to hint at the approaching transition to autumn. In western cities such as Everett and Vancouver, average low temperatures generally hover around 55°F (12.8°C). The eastern regions, including Moses Lake and Kennewick, see nighttime lows usually varying from 55°F (12.8°C) to 60°F (15.6°C). The prevalence of sunny days persists in August, although occasional cloud cover may appear, especially in the western part of the state. Weather in August »

September ushers in a transitional period as Washington bids farewell to the height of summer and begins to welcome the first whispers of autumn. In the western locales of Bellevue and Tacoma, average low temperatures cool to 50°F (10°C), indicating the approach of fall. Weather in September »

October marks a deeper plunge into autumn, characterized by falling leaves and increasingly crisp air. In the western urban centers of Bellingham and Olympia, average low temperatures reach about 45°F (7.2°C), while in eastern cities like Walla and Wenatchee, nighttime lows range from 40°F (4.4°C) to 45°F (7.2°C). This month experiences a substantial increase in cloud cover and precipitation. Weather in October »

November in Washington State heralds the onset of winter as it continues the autumnal trend of cooler temperatures and increased precipitation. In western cities like Seattle and Everett, average low temperatures dip to about 40°F (4.4°C). Weather in November »

December in Washington State ushers in the full embrace of winter, complete with colder temperatures and increased precipitation in the form of both rain and snow. In the western part of the state, cities like Vancouver and Olympia see average low temperatures plummet to 35°F (1.7°C). Weather in December »