These are two of the most important words in the entire incubation process. If the incubator is kept at the incorrect temperature and humidity levels for a sufficient length of time (or if levels continually change), it interferes with the normal growth and development of the embryo, and unfortunately can stop the embryo developing further. Your temperature should be between 37.5°C – 38°C (99.5°F – 100.5°F) with the humidity between 50 and 55 percent. For the last stretch of the incubation process, the humidity gets cranked up to 65 percent - but more on that later.