"...It may already be too late by then. Home Depot/Lowes can be a madhouse when there is a hurricane threat, all types of screws will be sold out, and the lumber will be gone. You want to have both screws and wood on hand already, and the screws you get should be based on what your house is made of. If you have a wood frame house, then deck screws should work fine. If you have a masonry, or concrete house, then you may want tapcons, concrete machine screw anchors, or wedge anchors, "Keep in mind that with wedge anchors, they are permanant, once they are set, there in there for good, the idea though is to have holes pre-drilled in the wood or shutters, so you can mount them with wing nuts..."

Finally someone says what I have thought for years. Every season see people at the "lumber" type stores, fighting for sheets of plywood. I have always wondered why anyone who lives in hurricane country would not have their home pre-setup like that...