Well, the weekend forecast is definitely "iffy," with temps in the 40-50s in the mountains -- maybe much lower than that -- but here's a trip for hard-cores who might not mind getting wet or even getting into some snow ...
Drive up Idaho 21 past Idaho City to Mores Creek Summit, and either hike/bike up to the top of Sunset Mountain Lookout (directly south of the highway) or hike/bike to the top of Pilot Peak, followed by an optional big 14-mile downhill cruise back to Idaho City (shuttle required).
Sunset L.O. and Pilot Peak are great destinations in the summer or winter. It's a 5-mile trip to the top of Sunset, and 3.8 miles to Pilot, so it's a steeper climb to reach Pilot Peak. You have to climb over 2,000 vertical feet to summit either one. Both of the routes are featured in Boise Trail Guide: 75 Hiking & Running Routes Close to Home and in Mountain Biking Idaho.
Both of them are equally fun. Great views of the Boise National Forest open up as you gain elevation, culminating in a great view at the summit. This weekend, the view may be obscured by weather ... who knows? To this powder hound, it's profoundly invigorating to cruise through a few inches of fresh snow, thinking about the promise of a great ski season ahead with tons of fresh *pow*.
Note: If you want to climb Pilot Peak and take the optional descent into Idaho City, it's a 20.8 mile ride through ponderosa pine and Douglas-fir forests; 14+ miles of it is downhill. Click on Mountain Biking Idaho and look up page 62-67 for a detailed description.
Stop in Idaho City on your through and check out the frontier downtown. Great food and drink and genuine hospitality.
- SS