Abstract: A temperature indicator system includes a temperature sensing assembly attachable to a beverage container. The temperature sensing assembly includes a temperature sensor in the form of a thermometer and a temperature scale against which the user may read the temperature of the contents of the beverage container. The sensing assembly may be provided on a beverage container from the point of sale in the retail store, or may itself be purchased and attached to a beverage container by means of either an adhesive backing or a magnetic strip. In one embodiment, the sensing assembly is fitted to a beverage container-encasing insulating sleeve. Optionally the temperature sensing assembly includes a region upon which the user of the beverage container may leave a personalizing mark, such as a pen marking or a fingerprint.