Fly Navy,
I'm in Northern Calif and i have mine in the attic and there has been no ill effects at all to the diecast planes.I will go up there about every 3 months to check on them and happy to say no problems.
I use the same Rubbermaid Bins that HWorth just stated they come in very handy.
Only one little problem....My attic is getting a little crowded  
JP |
Maybe you should consider buying less
I know its tough but it can be done its like stopping smoking. Maybe someone should start up DCA (Dieast Anonymous). Seriously though my extras are stored in vacuum bags that are normally used for clothes and then then in plastic boxes in my loft.