Abstract: The invention relates to a method and apparatus for equalizing the temperature profile of glass sheets in a roller-equipped furnace included in a horizontal tempering plant. At least in the early stage of a heating cycle, the upper surface of a glass sheet is exposed to an intensified convection heat effect by blasting air into the furnace from blasting pipes (3) located close to the upper surface of a glass sheet. This blasting compensates for the vigorous heat transfer to the lower surface of a glass sheet in the early stage of a heating cycle, which is caused by hot rollers. The blasting range and spot is manoeuvred in the longitudinal direction of a furnace in a manner that, at any given time, the blasting is only applied to that longitudinal section of a furnace in which a movable glass sheet is located at a given time.