High temperature affects berry composition, especially titratable acidity, total soluble solids, and anthocyanin content. Vitis ficifolia var. ganebu, a wild grape of sub-tropical origin with a low chilling trait, develops good coloration in its natural habitat, where daytime and nighttime temperatures are high during the berry ripening stage, while V. vinifera ‘Muscat of Alexandria’, a table grape, has large berries and high sugar content, hence, it was hypothesized that hybridizing V. ficifolia var. genebu with V. vinifera would improve the sugar content and reduce titratable acidity compared to V. ficifolia var. ganebu and retain berry color even under high temperature conditions. The aim of this study was to investigate the influence of temperature on the berry composition of ‘Kadainou R-1’, an interspecific hybrid wine grape derived from V. ficifolia var. ganebu × V. vinifera ‘Muscat of Alexandria’. Potted ‘Kadainou R-1’ vines with their ownroots were subjected to continuous temperatures of 20, 25, and 30°C in a phytotron during the berry-softening stage. Berries were harvested 15, 30, and 37 days after the vines were placed in the phytotron. Titratable acidity was lower at 30°C than at 20°C, while total soluble solids were highest at 25°C. Accumulations of glucose and fructose were higher at low rather than high temperatures. Total anthocyanin content (mg·g⁻¹ of fresh weight) was significantly reduced at 20 and 30°C but not at 25°C. Flavonol content was highest at 25°C. The present study revealed that ‘Kadainou R-1’ grapes can produce optimum berry quality in locations where the night temperature reaches 25°C without significant loss in berry quality.