SISI

Crews strengthen community protection lines as fire burns along Agnes Creek

The Sisi Fire is burning through remote, rugged terrain in the Okanogan-Wenatchee National Forest northwest of Stehekin, with the most active spread occurring along Agnes Creek on its northwest flank. Over the last 72 hours, fire crews removed hazard trees along Stehekin River Road to secure handlines while engines patrolled valley communities. Firefighters continue working to construct and reinforce community protection lines designed to tie directly into Lake Chelan.

Evacuations and Closures

• Chelan County Emergency Management maintains active evacuation levels for surrounding areas through its interactive mapping system as of September 10.
• Portions of the Pacific Crest Trail along Agnes Creek, along with additional trails and cross-country zones in North Cascades National Park, remain closed as of September 10.
• A Forest Closure Order and campfire prohibition remain in place across the Wenatchee River and Entiat Ranger Districts as of September 10.
• A Temporary Flight Restriction remains in effect over the incident area, barring unauthorized drone flights as of September 10.
• Boaters on Lake Chelan must remain near the shoreline and stay clear of aircraft scooping water as of September 7.

Impact

Wildfire smoke continues to degrade air quality across nearby communities, prompting regular smoke forecasts and health advisories from regional environmental authorities. No structural damage or injuries have been reported.

Conditions and Outlook

Gusty west-northwest winds will ease over the coming days as cooler temperatures, improving humidity recoveries, and increasing chances of weekend rain move into the region. Fire activity is expected to continue in steep drainages and heavy fuels, with torching and flanking possible on uncontained flanks. Crews plan to continue chipping roadside debris, completing containment lines toward Lake Chelan, and using helicopter water drops to slow progression along ridgetops.

Cause and Context

Lightning ignited the blaze on August 14, 2026, approximately ten miles northwest of Stehekin. The fire is burning through heavy dead and down timber within and surrounding the 2004 Sisi Ridge burn scar.

Official updates current through September 10, 2026.