Warm season turf is in full swing at 80-95 degrees, and cool season turf between 60-75. You will want to aerate when the grass is actively growing.Warm season turf (ie Centipede) should be aerated in the growing season or just prior to. Aerating in the fall is OK, but will not have any benefit. May actually harm the grasses ability to protect itself through a cold winter depending on exact conditions. If you are seeding Centipede you should do that early Spring once the grass has greened up.