Cedar Stair Treads
Even though I don't highly recommend using Western Red Cedar for stair treads or risers, it can be used on exterior stairways. Even though it's soft, it weathers well, but could turn gray, over time, if exposed to the sun without any protection.
Cedar is another softwood that scratches easily and
won't make the best stair tread, especially in high traffic areas. If
you're building a stairway on the outside of your home, for a
patio, you can use Cedar, but it wouldn't be a bad idea to protect it
somehow with something more durable, like a nonskid stair tread.
Special Note: Even though I don't recommend using Cedar, Redwood or other Softwoods for stair treads, some architects and designers are looking for a specific look that only these Softwoods can produce. Some home designers are actually looking for a rustic look and the faster the stair treads wear down, the better.
Gluing = Excellent, as a matter of fact, every once in a while you will need to glue a knot back into some of your stairway parts, if you use Cedar, for your stairs. They actually sell a tight knot grade of Cedar and I recommend using it, for stairs or decks.
Sanding = Excellent, as a matter of fact, it can be too easy to sand. Be careful when sanding Cedar, because it is a soft wood and can easily become damaged.
Staining = Good, I don't recommend staining Cedar, but it can be stained, with little effort. Any lumber that has different colors running through out the boards, could create color variations, that you weren't expecting.
Nailing = Excellent, it's one of the softest woods I've ever worked with and I can't think of one time, I've ever needed to pre-drill a hole, before using a screw or nail. Try to avoid nailing through knots, because they often split or are extremely difficult to nail for.
Wear And Tear = Fair, like I said earlier, I wouldn't use Cedar for stair treads or risers, because it scratches easily.
Janka Hardness Scale = 350