The temperature and humidity range that can be controlled by an incubator depends on the specific model and brand. However, for optimal hatching conditions, the temperature range should be between 99°F and 100°F (37.2°C to 37.8°C) with a relative humidity of around 50% to 55% for the first 18 days of incubation.
During the final three days of incubation, the humidity should be increased to around 65% to 75% to help the chicks hatch successfully. The temperature should remain the same during this time.
It is important to monitor the temperature and humidity levels regularly using a thermometer and hygrometer, and adjust the settings on the incubator as needed to maintain the optimal conditions for hatching.