Genetic variability in a crop population is essential for successful plant breeding. Fifteen cucumber (Cucumis sativus L.) genotypes were evaluated in the greenhouse under the warm condition to estimate the magnitude of their genetic variability and heritability as also morphological and pomological characteristics. Genotypes were also classified in to five groups based on the performance and determination of the highest discriminating characteristic that accounted for more significant variability using cluster analysis and principal component analysis (PCA). The measured characteristics were cucurbit chlorotic yellows virus and fungal severity, off-type plant, stem, internode, leaf, petiole, fruit and fruit trail length, leaf width, male flower percentage, fruit color and groove, fruit diameter, fruit fresh weight, fruit dry matter and ash percentage, fruit pH, EC and TSS, fruit yield, and total fruit number. The IR4 and IR5 genotypes showed the highest fruit yield (460.85 and 425.86 kg/plot) and number (108.72 and 84.22 fruit/plant). IR11 had the highest fruit length of 16.60 cm. High broad-sense heritability was associated with all the traits except for cucurbit chlorotic yellows virus and fungal severity, fruit pH, and total fruit yield. Cluster analysis and its comparison of means showed that IR4 and IR5 from the fifth cluster expressed the best agronomic traits and yield potentials in the warm condition (40°C/32°Cday/night). Hence, selection for any characteristic would favor genotypes in these clusters. The PCA involved fruit dry matter and TSS as the most discriminating trait that accounted for more significant cucumber variability, which should be considered in cucumber improvement programs.