shd3920, If the rubber bands were in good condition before they were left out in the cold, they will be fine once they warm up. The cold will stiffen them, like most rubber product's, but the cold will not deteriorate the rubber ie; cause dry-rot or cracks. This happens when the rubber is subjected to certain chemicals, and, with age. ( I check myself daily )

Its like changing tires. Roll a tire out of an unheated shed and try to mount it on a rim. The words you will utter are not to be spoken in front of children or clergy! However...let the tire warm up by either soaking it in a drum of heated h2o or let it stand in a heated garage for a few days, and it will form to the rim like butter!

It would be interesting to take those frozen rubber bands, let them thaw out (at least three days), and give them the stretch test. Also inspect for deterioration.