Winter on I-5 Between Redding and the Oregon Line

I-5 is the West Coast's main north-south freight route, and the stretch from Redding to the Oregon border is where it stops being a valley freeway. The road follows the Sacramento River canyon, climbs past Mount Shasta and crosses Siskiyou Summit before dropping into Oregon. On a winter day the weather can change from rain to heavy snow in less than an hour of driving.

Why this stretch catches people out

Drivers heading north from the Bay Area or Sacramento often leave in rain and assume it will stay rain. It frequently does not. The climb north of Lake Shasta is steady, the canyon holds cold air, and the higher country around Mount Shasta and the summit gets real snow. Add heavy truck traffic on long grades, and a storm can bring the whole corridor to a stop.

Chain controls on a truck route

Caltrans' rules are the same here as anywhere in the state. When signs say chains are required, you must stop and put them on, and the CHP can cite and fine you if you do not. Caltrans says there is usually about a mile between the "Chains Required" signs and the checkpoint where you install them, and that control areas can change quickly from place to place.

• R-1: chains required, except passenger vehicles and light trucks under 6,000 lb with snow tires on at least two drive wheels, which must still carry chains.
• R-2: chains required, except four-wheel and all-wheel drive vehicles with snow-tread tires on all four wheels, which must carry traction devices.
• R-3: chains or traction devices on every vehicle, no exceptions.

On a corridor this busy with trucks, a single spun-out rig on a grade can stop everyone behind it. Expect holds even when you are properly equipped.

Plows and chain-up areas

Caltrans asks drivers to stay at least four car lengths behind snowplows and snow-removal equipment, and to refrain from passing them or pass only with extreme caution, because operators are focused on the snow and cannot always watch for cars. Trucks spreading brine, sand or cinders carry "Stay Back" signs for a reason: the material can spray across several lanes.

When you chain up, pull completely off the traffic lanes into the chain area, turn on your hazards, and work on the side away from traffic if you can. Wear something bright. The roadside of a busy interstate in falling snow is one of the most dangerous places you will stand all year.

Planning around a closure

1. Check QuickMap before you leave and again in Redding. Redding is the last big decision point.
2. Be ready to stop for the night in Redding or one of the mountain towns rather than pushing into a storm after dark.
3. Fuel up, and carry water, food, warm layers and a phone charger, in case you sit for hours.
4. Cross the high country in daylight when you have the choice.
5. Check Oregon's conditions separately if you are going past the border; the road does not get easier at the state line.

Rental cars, visitors and coverage

If you are in a rental, read the agreement before the trip, because some rental contracts restrict the use of chains, and that leaves you stuck at an R-1 or R-2 checkpoint. Out-of-state drivers face exactly the same chain rules as Californians.

A slide into a ditch or a guardrail on ice is commonly a collision claim, and a tow from the Siskiyou high country can be long, so it is worth knowing your roadside program's mileage limit. Deer are out on this stretch too, at dawn and dusk especially. You can have your collision and roadside coverage checked before the next winter trip north.