Like the rest I leave mine in the hopper, but my grill is under my patio in a spot where it can't get wet. I use my grill so often there hasn't been time for an issue. I am south Louisiana and humidity or condensation has yet to form in the hopper. I keep my extra pellets in 20 qt sterile gasket boxes. I have been using these for years for all sorts of stuff and they just so happen to hold a little over 20 pounds of pellets and fit under my grill. I can fit 3 under there but 2 fit nicely with room to spare.
Link: 20qt Sterilite Gasket Box