The Leeds United boss will return to Glasgow after the trip to St. Andrew's on Tuesday.
Evans suffered a family bereavement in the build up to Saturday's defeat at Burnley but said he had no plans to miss either fixture.
Instead, the 53-year-old will wait until after the Blues meeting to return to his native Glasgow following the death of his sister-in-law.
“There were no doubts at all,” Evans told the YEP. “I’ll go to Birmingham and then head to Glasgow. In between I’ll focus on getting ready for Birmingham and then I’ll be in a car on Tuesday night. It’s a big loss to my family and especially my eldest brother.”
Leeds, who are without a win in four matches, are five points adrift of the Championship's top half but have an extra game on 12th-placed Wolverhampton Wanderers, who travel to Elland Road later this month.
The future of Evans, who is on a rolling contract until June 30, remains in doubt with the Whites making little progress since his arrival.
Had the season started on on October 19, the date he was appointed, Leeds would still be 15th in the standings - with nine wins, 10 draws and 10 defeats.
The Scot's predecessor Uwe Rosler was sacked following a slow start to the campaign which left the Yorkshire side in 18th place.