Plant growth duration (maturity) is an important factor in development of yield in grain sorghum [Sorghum bicolor (L.) Moench]. The effects of genotype maturity on yield may vary among environments that differ in climatic factors such as temperature and photoperiod. A study was conducted to determine the relationship of grain yield with maturity of 46 sorghum hybrids evaluated in replicated field yield trials at several locations across Nebraska and Kansas in 1978 and 1979. The locations varied in day/night temperature and rate of growing degree unit (GDU) accumulation during the growing season, and multiple trials at a location were conducted with different agronomic treatments such as planting time (early, medium, late) and plant population (low, medium, high). Simple correlation coefficients were computed between yield and the number of days from planting to flowering and the number of days from flowering to physiological maturity (grain‐fill period) in each environment. A highly significant and positive correlation between yield and days to flowering was found in environments with relatively high night temperatures and high rate of GDU accumulation. This correlation, however, was significantly negative in cool environments with low night temperature and slow accumulation of GDU. Correlation of yield with the number of days in grain‐fill showed that longer grainfill periods generally favored high yields. This relation was especially found in cool environments with delayed maturity, where the majority of high yielding hybrids appeared to have compensated the yield reductions due to delayed flowering by prolonged grain‐fill period. We suggest that in such environments hybrids with early flowering and a long grain‐fill period would be desirable.