Eggs for Incubation

Its February here in KY, I have started selecting eggs for the hatch, incubator. My question, what affect does the weather have on the eggs if they have been in the cold prior to gathering of the eggs. They haven't frozen, but some days have been very cold. It just seems that the eggs that were gathered on the mild days have hatched at a higher rate than the eggs gathered on those cold days. If the colder weather has a bearing on the lower incubation rate, I will just keep them for consumption. Any feedback will be helpful.