Seattle to Vancouver — Weather & Driving Conditions
Driving from Seattle, WA to Vancouver, BC? This 143-mile route follows I-5, BC-99. TripCaptain checks the weather at every stop along the way — not just at each end — so you can see where conditions change before you pick a departure time.
What to watch for on this route
TripCaptain flags black ice, dense fog, heavy snow, high wind, heavy rain, and low visibility segment by segment between Seattle, WA and Vancouver, BC, and gives the trip a clear Hazard Score™ — a 0-100 read where higher is safer.
- Dense Fog: Low-lying farmland around the Skagit and Nooksack river valleys traps dense morning fog across I-5 between Mount Vernon and Bellingham.
- Freezing Rain: Cold air draining out of the Fraser Valley produces freezing rain near the Peace Arch border crossing — a hazard rare elsewhere on the route.
- Flooding: Atmospheric river storms push the Skagit and Nooksack rivers over their banks; I-5 has flooded near Mount Vernon during severe November rain events.
When to go, season by season
- Spring (Mar–May): Frequent rain but mild. River levels run high with snowmelt. Generally easy driving with pleasant conditions by May.
- Summer (Jun–Aug): Best season — dry and clear. Wildfire smoke drifting from the BC interior can occasionally reduce visibility in August.
- Fall (Sep–Nov): Atmospheric river storms begin in October, bringing heavy rain and flood risk in the Skagit Valley. Fog increases on cold mornings.
- Winter (Dec–Feb): Mostly rain, but Fraser Valley outflow can cause freezing rain near the border. Border wait times grow in cold weather.
Pick the safest time to leave
Compare departure windows for Seattle to Vancouver and choose the one with the lowest risk and the arrival time you want.
Fuel, EV range, and rest stops
See a weather-adjusted fuel or EV energy estimate for the drive, sensible break points across the 143 miles, and a packing list matched to the conditions ahead.