So you've probably read the earlier posts here and here about our bike trip to Stub Stewart State Park over New Years. It was a lot of fun! And as we were taking the long, long MAX ride back from Hillsboro, bikes swinging on the hooks, I felt like taking another overnight bike excursion soon.
Of course there are issues that need to be dealt with when it comes to winter bike touring. Besides some campgrounds being closed during the winter, the two key ones are weather and dark. Here in the west-of-Cascades Northwest we're blessed with relatively mild but damp weather in winter. Daytime highs range from 40-50 degrees Fahrenheit (4-10C), and night-time lows somewhere between that and freezing. And there's always the chance of rain. So riding is possible and camping can be tolerable with decent cold weather and wet weather gear.
Personally I don't enjoy setting up/taking down a tent in the rain* and then huddling in a small tent during the long dark hours. But here in Portland we're spoiled, and we get more options, like yurts and cabins.
Yurts and cabins are available in some Oregon and Washington State Parks. Yurts are large rounded semi-permanent tents like the type nomadic tribes use in Mongolia. Cabins are...cabins. Both yurts and cabins have beds, tables, chairs, and most importantly for me electric lighting and heating. You'll still need to bring your own bedding and cooking equipment (stoves need to be used outside of the structures, though.) But there's no tent to worry about putting up! You already have a warm and dry place to get out of the rain. And these places make great spaces for reading, drawing, knitting, card games, etc.
In Oregon yurts and cabins are pretty inexpensive during the winter months. Yurts run around $30 per night, cabins $45 and up. Washington rates are a bit higher, in the $55-65 range. The price is a bit steep for a solo camper, but becomes more economical if you can get more people to come along (they sleep up to 5.) Snagging an available one is a lot easier in winter, however they can fill up on weekends. It's always wise to sink the extra $8 (in Oregon) to make a reservation, because it would suck if you rode all the way to the park of your choosing to find no yurts/cabins available, you're without a tent, and it's almost dark.
There are a few options around Portland. Stub Stewart (where we stayed on New Years) is approx. 22 miles NW from Hillsboro (where the MAX ends, riding from Portland would make it 40 miles) in the Coast Range. Champoeg is approx. 40 miles south of Portland on the banks of the Willamette. Battle Ground Lake is north of Portland in Clark County, Washington, an easy 25 mile ride from the Expo Center Yellow Line MAX stop. Paradise Point is also north in Clark County, also approx. 25 miles.
If one doesn't mind "cheating" a little bit and taking the bus (as the closest coastal option is a 70 mile ride from Hillsboro, hard to accomplish in the winter without riding into the night), three Oregon North Coast parks have yurts: Cape Lookout (cabins also), Nehalem Bay, and Fort Stevens, plus Cape Disappointment across the Columbia on the Washington coast. And if one's really ambitious and doesn't mind a long ride, a good climb, and the possibility of snow at the end, Silver Falls is about 60 miles south of Portland. At 2,000 feet in elevation, the falls are beautiful with ice!
Beyond that, there are plenty of hotels and motels found in the outlying areas. Winter months mean a better chance of snagging a good deal and an easier chance of finding one with availability on the fly. If you are not planning on reserving a room, make sure you have backup options in case your chosen destino falls through.
As for the riding, touring sans tent means a slightly lighter load, but you might make it up in extra clothing! Good layers are the key. Choose wool or warm synthetics, avoid cotton like the plague because once it gets wet, it will suck away your heat. Bring enough clothes so you can change out of a wet set. Bring a good rain jacket, cape, etc. Warm socks! Opt for shorter days, maybe 30-40 miles, because during winter months you'll have 8-10 good hours of daylight. Save the 60 miles and up for summer. And take warming up breaks every 10 miles or so. Find yourself a cafe, bar, restaurant, order a warm beverage and thaw out your feet!
*I know that one should always expect a chance of setting up a tent in rain during a bike tour. But in winter here it's a given that it will rain.