This is normal for a reblooming iris. Do you know its name. I have a bloom open now and blooms stalks on two other irises. I don't usually have bloom into December but it has been warmer and so I am getting the joy of seeing an iris near Christmas. No they will not hold til spring and if it freezes before they open it will injure them. If they get near opening and the weather looks like it is going into the deep freeze you may want to consider tenting them or if the blooms are about to open you may cut it just before it does and bring it indoors to open...... this is a last resort.
