I-90 Snoqualmie Pass Corridor Road Conditions

Cross the Cascades on I-90 — Washington's primary east-west EV corridor. Review seasonal patterns and EV planning considerations for the I-90 corridor, then open your route in the planner.

Winter Pattern

Snoqualmie Pass receives 12-15 meters of annual snowfall, making it one of the snowiest highway crossings in Washington. I-90 over the pass closes multiple times each winter during heavy snowstorms and for avalanche control on the 23 avalanche paths that cross the highway. Traction tire requirements are enforced from November through March. The pass sits at only 921 m but its proximity to Puget Sound moisture makes it exceptionally snowy — wetter and heavier snow than interior mountain passes.

EV-Specific Notes

The climb from North Bend (130 m) to the summit (921 m) is moderate by mountain-pass standards but still costs extra energy over the flat equivalent. Precondition your battery in Seattle before departure in winter. The Ellensburg Supercharger on the east side is the key charging stop for westbound crossings. Heavy wet snow and low temperatures can combine to noticeably cut range compared to summer conditions.

Frequently asked questions

How often does I-90 close over Snoqualmie Pass in winter?

I-90 over Snoqualmie Pass closes an average of 10-20 times per winter season, with closures ranging from 1 hour for avalanche control to 12+ hours during major storms. The most closure-prone months are December through February. The 23 avalanche paths that cross I-90 make it the most actively controlled avalanche zone on any US interstate. Check official road-condition alerts for real-time status before departing.

What traction requirements exist on Snoqualmie Pass for EVs?

Traction tire requirements run from November 1 through March 31. At minimum, all vehicles need approved traction tires (M+S rated or better) on all drive axles. When conditions worsen, chains are required on all vehicles without AWD/4WD and approved traction tires. Most AWD EVs with winter tires are exempt from chain requirements, but carrying chains or AutoSocks is strongly recommended. Tesla advises against tire chains — consult your vehicle manual for approved alternatives.

Where can I charge my EV near Snoqualmie Pass?

On the west side, North Bend has Level 2 chargers and is the last town before the pass. The Issaquah Supercharger is about 30 km west of North Bend. On the east side, the Ellensburg Supercharger (about 50 km from the summit) is the primary fast-charging stop. There are no DC fast chargers at the summit itself — the ski areas at Snoqualmie Pass have limited Level 2 options. Plan your charge level carefully for the crossing; do not rely on finding a charger on the pass.

How much range does Snoqualmie Pass cost an EV compared to flat driving?

The westbound crossing (Ellensburg to Seattle) climbs about 790 m from the Kittitas Valley floor to the summit, then descends 800 m to the Puget Sound lowlands. The net climb costs more energy than the equivalent flat distance. In winter, cold and snow tires add still more on top. The eastbound crossing is similar in total energy cost. Heavy wet Cascade snow is harder going than dry powder — a factor unique to this pass compared to drier Rocky Mountain crossings.

What is the best time of year to cross Snoqualmie Pass in an EV?

July through September is optimal — the pass is reliably open, temperatures are mild (reducing HVAC load), and there are no traction requirements. The Pacific Northwest dry season means minimal rain and no snow concerns. October is borderline — the first snow can arrive by mid-month. Avoid December through February unless your trip is time-critical; the combination of short daylight, heavy snowfall, frequent closures, and a real drop in winter range makes winter crossings stressful for EV drivers.

Is there an alternative to I-90 over Snoqualmie Pass for EVs?

US-2 over Stevens Pass (1,238 m) is the main alternative, running about 120 km north. Stevens Pass is higher, narrower, and has no avalanche-control infrastructure — closures are less controlled and can last longer. It also has fewer charging options. I-90 over Snoqualmie is the preferred EV crossing because of its lower elevation, wider lanes, professional avalanche management, and better charging infrastructure on both sides. For extreme situations, WA-14 along the Columbia River Gorge avoids mountain passes entirely but adds 3+ hours to Seattle-to-eastern-Washington trips.

Can I use my EV's regen braking effectively on Snoqualmie Pass?

Yes — the descent from the summit is steep enough on both sides to generate meaningful regen energy. Westbound, the 12 km descent from the summit to North Bend drops 790 m and gives back a useful amount of charge at moderate speeds. Eastbound, the descent to the Kittitas Valley is more gradual but still provides useful recovery. Set regen to maximum before the descent. In snowy conditions, reduce regen intensity to avoid locking the drive wheels on slippery surfaces — some EVs do this automatically when traction control is active.

What should I carry for an EV trip over Snoqualmie Pass in winter?

Beyond standard winter gear (blankets, warm clothing, snacks, water), EV-specific items include a portable phone charger (to access real-time road conditions during closures), tire chains or AutoSocks approved for your vehicle, and a 120V extension cord in case you need an emergency Level 1 charge at a ski lodge or gas station. Keep your battery above 50% when entering the pass corridor. Set up official road-condition alerts for I-90 closures. If a closure is announced, do not attempt to race to the pass — the closure gates close quickly and being caught mid-pass is the worst outcome.

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