When you feel his or her forehead, it feels warm 100.4 degrees Fahrenheit 3 months old and has a temperature of 100.4 degrees https://www.babycenter.com/0_fever-in-babies_84.bc 38 degrees body temperature fever 6 months and has a temperature of 103 degrees 3 months old and has a temperature of 100.4 degrees 6 months and has a temperature of 103 degrees When you feel his or her forehead, it feels warm 100.4 or higher When you feel his or her forehead, it feels warm http://www.babycenter.com/0_fever-in-babies_84.bc 103 degrees http://www.babycenter.com/0_fever-in-babies_84.bc