Issaquah Alps, WA

Today’s Forecast:

Today’s Report:

About Issaquah Alps

Issaquah Alps is a Washington destination for the connected Cougar, Squak, and Tiger mountain trail systems along the eastern Seattle foothills.

Make the Most of a Issaquah Alps Day

Choose a specific mountain and trailhead before departure. Mud, low clouds, wind exposure, and parking pressure vary among the three trail systems.

Weather Tips for Issaquah Alps

• Check rain timing, wind, visibility, temperature, and local access before choosing the day’s route.
• If thunder is possible, finish exposed viewpoints, ridges, golf, or event grounds early and keep substantial shelter close.
• After steady rain, favor paved or well-drained surfaces until natural trails recover.
• Summer smoke, winter access, shoulder-season closures, and shorter fall daylight can matter even during an otherwise mild forecast.

Nearby Towns and Areas

This page can also be useful when planning outdoor time near:

• Cougar Mountain
• Squak Mountain State Park
• Tiger Mountain
• Issaquah
• Lake Sammamish
• Newcastle
• Poo Poo Point

Plan Around the Conditions

Use the forecast to choose the best version of a Issaquah Alps day. Match wind, precipitation, smoke, water conditions, trail surfaces, road access, temperature, and daylight to the activity that gives your group the safest and most comfortable plan.

7-Day Forecast for Issaquah Alps

Issaquah Alps Weather by Season

Winter

Winter at Issaquah Alps is cool and wet west of the Cascades, with occasional lowland snow or ice. Shaded roads, bridges, docks, and trails can remain slick after other surfaces clear.

Spring

Spring around Issaquah Alps brings changing conditions, rising rivers, wet trails, and lingering mountain snow. Give muddy natural surfaces time to drain and avoid widening trails. Mountain and eastern thunderstorms become increasingly possible later in the season.

Summer

Summer at Issaquah Alps is usually the driest and most dependable season, but wildfire smoke, fire restrictions, heat, and afternoon thunderstorms can interrupt plans. Start exposed routes early and carry enough water. Dry vegetation makes local fire rules especially important.

Fall

Fall at Issaquah Alps brings cooler temperatures, shorter daylight, changing color, and the return of wetter weather west of the Cascades. Early snow or ice may reach upper roads before lower elevations. Check seasonal facility hours and allow extra time on busy event or salmon-viewing weekends.

Key Climate Data Points

• Annual average temperature: around 49–51°F near the foothill towns, using the relevant local or regional elevation context.
• Annual snowfall: valley snow is usually limited, but upper trails can receive significant snow, with substantial year-to-year and elevation variation.
• Warmest months: July and August are normally warmest.
• Coolest months: December and January are typically coolest.
• Wettest season: November through January.
• Driest season: July and August.
• Best outdoor window: May through October after natural-surface trails drain.