The Comedy Central show last week substituted repeats for scheduled shows on Wednesday and Thursday. At the time, the network said only that the cancellations were because of "unforeseen circumstances."
Colbert is expected to address his absence on Monday. His 91-year-old mother, Lorna Colbert, is ill.
Earlier on Twitter, Colbert thanked those who had offered "thoughts and prayers."
Colbert's father, James Colbert, and two of his brothers were killed in an airplane crash in 1974.
