Mount Si
Today’s Forecast:
Show Alert Details & Instructions
Today’s Report:
Hiking
Excellent for hiking. High near 78°F. Low rain risk (11%).
- Temp: Marginal weather factor
- Rain: Favorable conditions
- Wind: Favorable conditions
- Thunderstorm: Favorable conditions
Camping
Excellent for camping. High near 78°F. Low rain risk (11%).
- Temp: Marginal weather factor
- Rain: Favorable conditions
- Wind: Favorable conditions
- Thunderstorm: Favorable conditions
Outdoor Events / Activities
Excellent for outdoor events / activities. High near 78°F. Low rain risk (11%).
- Temp: Favorable conditions
- Rain: Favorable conditions
- Wind: Favorable conditions
- Thunderstorm: Favorable conditions
About Mount Si
Mount Si is a Washington destination for the Mount Si and Little Si trailheads, North Bend valley, nearby river access, and foothill recreation.
Make the Most of a Mount Si Day
Start early enough to manage parking, heat, and daylight. Snow, ice, summit wind, and low clouds can make upper conditions much different from North Bend.
Weather Tips for Mount Si
- Compare valley and high-elevation forecasts because snow, wind, clouds, smoke, and temperature can change sharply with elevation.
- If thunder is possible, finish exposed viewpoints, ridges, golf, or event grounds early and keep substantial shelter close.
- Check overnight lows, wet ground, fire rules, drainage, and the nearest substantial shelter before settling into camp.
- 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:
- North Bend
- Little Si
- Middle Fork Snoqualmie River
- Teneriffe Falls
- Rattlesnake Lake
- Snoqualmie
- Olallie State Park
Plan Around the Conditions
Use the forecast to choose the best version of a Mount Si 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 Mount Si, WA
Mount Si Weather by Season
Winter
Winter at Mount Si brings mountain snow, ice, short daylight, and changing road or trailhead access. Higher routes may close while lower valleys remain rainy, so check current transportation notices.
Spring
Spring around Mount Si 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 Mount Si 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 Mount Si 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 48–50°F near North Bend, with much colder summit conditions, using the relevant local or regional elevation context.
- Annual snowfall: lowland totals are modest, while upper Mount Si commonly holds winter snow and ice, 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: late spring through early fall when upper trails are clear.