I've had success planting small spring bulbs (crocus, small daffodils, small tulips, anemones) up until about Halloween. Then it does get too cold. I think we're at least a couple of weeks behind you (in MN), weatherwise, so it's still warm enough to plant new ones. They need about four weeks before the ground gets cold to get themselves settled for next year, and we've only had one frost so far this season.

We plan on being at Windycon, barring schedule collapse or other catastrophe.