Do-it-yourselfers must be on guard for day-to-day temperature changes and sudden showers that can mar many spring projects like painting, caulking, driveway sealing and deck finishing, among others.

Q Our kitchen cabinets are 1970s knotty pine in very good condition. We painted them using a good primer and paint, but after about six months we can see the knots through the paint. What can we do ...