The main aim of the experiments was to demonstrate the possible correlation between developmental and morphological traits and yield components under variable climatic conditions. For this purpose, a collection of 188 wheat (Triticum aestivum L.) genotypes with a heterogeneous gene pool was included in a 3‐yr field experiment applying normal and late sowing dates each year. Under these conditions, almost all the traits were significantly influenced by the genotype, which had the greatest effect on the morphological traits and yield components (explaining 20–58 and 50–60% of the phenotypic variance for the two trait groups, respectively). In the case of plant development, however, the year effect, particularly in the late sowing treatment, was more significant than that of the genotype. Sowing date had the strongest effect on the early developmental phases, explaining 50% of the phenotypic variance, whereas the year had a significant influence on the late developmental phases, being responsible for 37 to 53% of the phenotypic variance. The turning point between the two factors was during the first phase of rapid stem elongation. The environmental driven variation in developmental patterns led to significant variation in yield‐related traits, which ranged from 4.6 (average thousand‐kernel weight) to 16.3% (average seed number) with normal sowing, and from 2.9 (average seed weight) to 29.4% (average thousand‐kernel weight) under late sowing conditions. The significance of the two intervals, from sowing to the start of rapid (intensive) stem elongation and from the start of stem elongation to the boot stage (Z49), was most apparent in the case of yield‐related traits.