When it's below a certain temperature, you have to layer up. I'm no lumberjack but I've always had an affinity for flannel shirts. There's something rugged about them, even when they are produced in fashion colors. Honestly, even when you're roaming a foreign state or exploring a forest, it doesn't hurt to have a little pop of color to refresh the earth tones.
If you get a little overheated, my favorite thing to do is tie it around my waist like a punk kid in high school. All clothes have versatility but flannels are super fun to style. It also doesn't hurt that the soft fabric ends up making the shirt just as comfortable as sinking into the couch cushions when you're wearing your favorite sweatpants or PJs.
You can get yours from Lands' End, and....they're only $49.