Mount Si · Main Trail
Main Trail to the basin below the Haystack
The Route
A sustained forest ascent to a rocky basin below the Haystack.
- Main TrailheadForest switchbacks begin immediately
- Snag FlatOld-growth section beyond 1.5 miles
- Upper ForestSteeper climb and first views near 3.5 miles
- Talus & Rock BasinMain hiking endpoint below Haystack
Lower Forest & Snag Flat
Switchbacks begin just above the main trailhead. The grade eases after the first mile and a half through Snag Flat, where old-growth trees survived logging and fire. Beyond this flatter section, the route climbs more steeply through younger forest.
Upper Talus & Overlook
A small opening around 3.5 miles precedes the upper talus slope. The route continues up stone steps, crosses the rocks and briefly re-enters forest before the Snoqualmie Valley overlook. Stopping at the first rock opening is shorter than following the full trail to the basin.
Haystack & Return
The Haystack is the true summit, reached by a separate rough scramble from the hiking trail. This briefing ends below it. Returning on the Main Trail reaches the same lot; the Old Trail instead descends toward Little Si and a different trailhead.
Forest
The approach climbs through forest, including old-growth trees at Snag Flat, before continuing through younger forest on the steeper upper trail.
Talus & Rock Basin
WTA describes a talus slope after roughly 3¾ miles, followed by rocky terrain below the Haystack.
Approximate main-trail reference figures, not a measured personal itinerary. Endpoint is below the Haystack, not the true summit. Reference Set: 2026-10-23.
Weather
Current forecasts open at the providers below. NWS forecasts describe a terrain grid cell, not an exact summit.
Access
Mount Si Main Trailhead, North Bend, WA
Driving Approach
From I-90 exit 32, go north on 436th Avenue, left onto North Bend Way and right onto Mount Si Road. The main lot is about 2.5 miles along Mount Si Road, beyond LittleSi and before Teneriffe.
Parking & Site Rules
Discover Pass required; day use only. Dogs must be leashed and there is no garbage service. The DNR trail map prohibits parking outside trailheads on county and private roads.
Endpoint Distinction
The standard hiking route reaches the upper talus and rock basin. WTA describes Haystack's true summit as a separate rough scramble, not the maintained-trail endpoint shown here.
Source information checked 2026-10-23. Road snapshots are dated separately.
Reports
Main Mount Si Reports
This feed covers the main trail from Mount Si parking through Snag Flat to the upper basin. OldTrail and LittleSi reports use different starts; a Haystack summit report includes a separate scramble.
DNR Access Notices
The Mount Si conservation-area page supplies official parking, conservation-area rules and recreation alerts.
Links open the publishers’ report pages. Reports are not automatically imported or filtered to a forecast date.