What Is the Weather Like in Washington?

Snowmelt season creates flooding risk in valleys while mountain passes may remain closed through late May. Temperatures fluctuate wildly from the 30s to 70s°F, sometimes within the same day. Avalanche danger remains high through April — backcountry travelers need avalanche training and gear. Rivers swell with snowmelt making it prime whitewater season. Wildflowers begin appearing at lower elevations in May while mountains remain snow-covered. Be prepared for any weather when venturing out.

The short but glorious mountain summer brings warm days in the 75–90s°F with cool nights in the 40s–50s°F — perfect camping weather. Wildfire smoke from regional fires can blanket valleys for weeks, turning skies orange and degrading air quality to hazardous levels. Afternoon thunderstorms develop over the mountains daily, often bringing lightning that ignites new fires. July and August are prime hiking, camping, fishing, and mountain biking months. Higher-elevation wildflowers peak in July.

Aspen groves and larch trees turn brilliant gold against evergreen mountainsides from mid-September through early October. First significant mountain snow arrives by late September, signaling the transition. Hunting season is a major cultural tradition across the mountain states. Temperatures range from the 50s–70s°F in September to the 20s–40s°F by November. Fall storms can bring early season blizzards to mountain passes — carry chains and winter supplies when traveling.

World-class powder skiing across dozens of resorts in Colorado, Utah, Montana, Wyoming, and Idaho draws millions of visitors. Mountain valleys experience temperature inversions trapping cold air and fog for days while mountaintops bask in sunshine. Temperatures range from highs in the 20s–30s°F to overnight lows of -10 to -30°F during arctic outbreaks. Chinook winds along the front range can raise temperatures 40–50°F in hours. Snowmobiling, ice climbing, and backcountry skiing are popular activities.