I really do not know the answer but, as long as the eggs do not freeze,I think they still have a good chance of hatching.It takes a hen many days to accumulate a clutch of eggs to set on and I have heard that cold eggs go dormant until they are warmed back up again.
The optimum range of temperature is between 55 and 65 degrees. Higher, and the embryo is likely to begin developing. 71-72 degrees marks this point. Lower and the viable germ begins to degrade, with 45 and below considered to be the cutoff point.
However, there are untold numbers of people who will tell that they have incubated "too cold" eggs, or those stored in the fridge, successfully. The odds are not in favor of this and the viable hatches rate is probably going to be low. But with nature, variables are many and nothing is absolute.
I would suggest however, that eggs at or near freezing for more than 6 hours are probably goners.
I've been collecting eggs for hatching the past few days - it's still falling into the single digits here in WI overnight. I go fetch them very early in the morning, and a few times I've got to them while they were still warm, but they're usually cold when I get them.
I'm putting them in the 'bator this coming Wednesday, so I'll have to update you on whether or not they start to develop.