They should be fine. I'd punch holes in the bags, though. If you make a 3ft circle (or however big you need) of 4ft high vinyl coated wire it makes a handy bin and they'd keep in there as well.

tj

Meant to include the bin is for storing the leaves outside. The bags would be fine outside as well. Leaf mold is a wonderful resource.

tj

I have kept several garbage bags full of leaves over the winter. They stayed dry and didn't mold.

I wouldn't bring them inside, particularly if I'm punching holes (critters?). Mow them or shred them and then collect? (decreases bulk by about 80% and improves speed of compost). Is your compost pile limited in size so that you can't just add them to the top of the compost? I have a compost pile with leaves and grass mixed, and then I have a bin with just leaves composting "slowly."

Here is a link that might be useful: Garden Musings