Sand the drawers so they fit just a bit loose they will swell in higher humidity and you will not be able to open or close them this summer when you need to. And to keep them from coming open here is a simple way to secure them. Just drill a 1/4" hole in the top near the front left of the box and in each drawers bottom and box bottom. Make sure all five holes are lined up so you can insert a 1/4" dowel with a handle on it into each hole locking the drawers this will keep them shut in travel.