I recently set a batch of shipped eggs. Before I did so, I checked the accuracy of my digital thermometer by putting a ziplock bag full of water into the incubator over night. I measured the water bag's temperature and it measured one degree cooler than the digital thermometer's reading. I adjusted the incubator temp to 100.5 and set the eggs.
It has been a week, and on a whim I rechecked the water temperature. It measured dead on with the digital thermometer. It would seem I have been incubating the batch at an actual 100.5 instead of the assumed 99.5.
I am curious to know your thoughts on the situation. It is an old cabinet incubator, but it does fluctuate about 1 degree up or down throughout the course of the day, but I do adjust the thermostat regularly. Still, it would mean there have been times the eggs were exposed to 101.5 degree temperatures.
Ordinarily, with fresh eggs I wouldn't expect to see much of a difference except for a possible early hatch. But with shipped eggs, I sure am weary.