Six matches will be played on August 11, at Chester-le-Street, Edgbaston, New Road, Cardiff, Radlett, and Headingley.
August 4 will feature four Vitality Blast matches, at New Road, Headingley, Bristol, and Richmond.
Worcestershire will hope to keep pressure in pursuit of the top spot while Leicestershire looks to move out of the bottom.
Sunday will feature three Vitality matches: Derbyshire Falcons vs Lancashire Lightning, Northamptonshire Steelbacks vs Yorkshire Vikings, and Worcestershire Rapids vs Durham Jets.
Middlesex, Nottinghamshire, and Glamorgan will host Essex, Worcestershire, and Somerset respectively.
Worcestershire have won the tournament four times and Somerset once.