My house is 55 years old and still has the original stucco. On one exterior wall, there's a fine crack with paint peeling away on either side. Is there a way to repair stucco quickly and easily before the rains come, and is it a job that I can do on my own?
A bit of good news: From your description, it sounds like your crack is not due to the foundation settling. If you had noticed larger cracks and such accompanying signs as sticking doors and windows, then I would have recommended that you call in a foundation specialist. As it is, yes, this is a job any do-it-yourselfer can handle. And it's important work, so you're right to have been vigilant. If rainwater were to penetrate behind the stucco, you might have a bigger problem on your hands.
To repair stucco, you can use any number of commercially sold products. While some are designed to remedy larger gouges and holes, others are meant specifically to fix cracks like the one you describe. Quikrete, for example, manufactures a sanded (textured) acrylic caulk that's both easy to use and effective.
The first step may seem counterintuitive: Using a cold chisel and hammer, widen the crack to at least a quarter inch. The edges of the crack should be chiseled perpendicular to the wall. If possible, back cut the crack so that its base is slightly wider than its top. Then clear all loose debris from the crack with a wire brush.
Now use a standard caulk gun to apply the stucco repair compound along the crack. As you go along, trowel the patch so that it matches the surrounding stucco finish. Allow the repair to cure for 24 hours, then cover it with a water-based paint, preferably the same color as the home's exterior.
You may notice that despite having cured, the finished job feels flexible to the touch. That elasticity actually attests to the strength of the repair. Should the wall move slightly in the future, the patch will adjust rather than come undone. With the crack now properly repaired, you can rest assured that precipitation will not be able to get behind the stucco.