Nockamixon State Park, trails maintained by RideNox, on the northeast end of the lake. Parked at the Tower Rd lot. Upper 60s, near 70.
Upper section of Cold Spot trail, Hammer loop, and Haycock Run loop (though I cut off a section since this is my first time riding here). Fell two or three times but no major damage (arm scratches, and leg bruises where I hit the bike during my falls).
http://www.ridenox.com/