Exposed fruit of `Rosemarie' blushed pear (Pyrus communis L.) displayed daily fluctuations in color in response to temperature while color was more stable in other blushed and fully red cultivars. `Rosemarie' pears increased in redness with the passing of cold fronts, but rapidly lost red color during intermittent warmer periods. Studies on anthocyanin degradation in detached apples and pears indicated that preharvest red color loss was due to net anthocyanin degradation at high temperatures. In support, anthocyanin degradation in attached `Rosemarie' pears corresponded with a warm period during fruit development. Susceptibility to color loss was dependent on the ability of fruit to accumulate anthocyanin. This is due to an exponential relationship between anthocyanin concentration and hue at high pigment levels and a linear relationship at lower pigment levels. Blushed and red pear cultivars that accumulate more anthocyanin with lesser dependence on climatic conditions were less susceptible to fluctuation in color.