Remember, fevers are your body's natural response to infection, and not necessarily a sign that something serious is taking place. Low-grade fevers are generally not serious, are easily treated, and can wait until the morning to be evaluated by your doctor. Fevers of 101 to 103 (38.4 to 39.5 Celcius) are also generally not serious and can wait until morning to be evaluated, except as indicated below. High fevers of 104 (40 Celcius) or higher that quickly come down to 100 or 101 (37.8 to 38.3 Celcius) with the treatment measures below are also generally not serious and can wait until morning, except as indicated below.