Plan the Seattle, WA to Portland, OR drive with route-aware weather, transparent fuel estimates, and a clear-eyed comparison of your alternatives.
Moderate year-round. Atmospheric rivers cause heavy rain and hydroplaning risk along the I-5 corridor Oct–Apr.
Open the live RouteWeather planner → to see today's exact conditions for every waypoint on this drive.
This evergreen guide uses a 25 MPG example vehicle and a historical publishing assumption of $3.75/gal. Open the live planner for the current national weekly baseline or enter a price you observed.
| Metric | Value |
|---|---|
| Distance | 175 miles |
| Fuel needed (25 MPG) | ~7 gallons |
| Guide-only price assumption | $3.75/gal |
| Est. fuel cost | $18–$25 |
No station-level price or discount is claimed on this page. Use the live planner to find route-relevant station searches and verify the pump price before choosing a stop. How fuel estimates work.
Avoid Friday afternoons and Sunday evenings. Best: Tuesday–Thursday before 10 AM.
The Seattle to Portland drive is approximately 175 miles along I-5 South and takes around 3 hours under normal traffic conditions.
Drive or take Amtrak. Flying from SEA to PDX is rarely faster once you account for airport security and baggage. Amtrak Cascades is scenic and often the same time as driving with traffic.
Heavy rainfall from October through April is the primary hazard. Watch for hydroplaning on wet I-5 and reduced visibility near Chehalis, which sits in a low-elevation fog pocket.