I just did 15 splits about 10 days ago. 2 days after I did the splits, the temps dropped into the low 30'a. The nucs that were full of bees did pretty good. 2 of them had to be put in 10 frame hives on Sunday due to the number of hatching bees. I did lose 4 nucs, 2 because I did not have enough bees and 2 because too many bees went back to their original hive.
Be sure to add extra bees from brood frames and pull 3 frames of brood, and 1 frame of pollen and honey.