Well the absolutely safest thing is of course to unload completely. Going into a warm house from the cold outside will cause condensation. If the temps your hunting are moderate then this isn't an issue. All you need do is remove the cap and place a folded patch between the hammer and nipple. That will keep things dry and greatly reduce an accidental discharge. I keep my sidelock (flinter) loaded all season unless I get caught in the rain and just put a patch between the fling and frizzen.