Uguak was born in Egypt after his family had fled their native South Sudan to escape civil war. When he was eight months old, his family settled in Canada. Uguak grew up playing football but switched to basketball due to his height and slender frame. He attended Harry Ainlay High School in Edmonton, Alberta. Uguak led his team to back-to-back provincial titles. He committed to playing college basketball for New Mexico. He was the highest rated prospect in his class from Alberta.