At the end of January, you should absolutely be prepared for winter driving. At that time of year, the roads require chains or traction tires. If you are comfortable driving in the snow, you could get by with chains, but if you’ll find yourself white-knuckled on the wheel, I’d recommend 4-wheel drive and chains/traction tires to keep you and other drivers safe.
Hwy 26 is groomed and graveled regularly, but it has heavy traffic. If you’re planning to travel on a weekend between 3:00-5:00, be prepared for significant traffic, especially if there’s a holdup (which is not unusual). Portlanders love to ski, so Hwy 26 gets bottlenecked up on the mountain around Government Camp and Trillium Lake.
The road to Trillium Lake is partially maintained. Sometimes it’s groomed, but be prepared for packed snow, ice, and a bumpy ride.
When you head out for your adventure, remember to pack the following: chains that fit and you know how to install, extra hardy gloves for installing chains, an ice scraper, and extra layers to use while chaining up (it can be a dirty job). And of course, an insurance policy on your rental vehicle. You can also check the road conditions at https://tripcheck.com/, but remember that conditions can change rapidly.
Good luck on your adventure and happy trails!2