Wheat development is affected by nutrients, water, light, and other factors; but temperature consistently determines how quickly or slowly plants move ahead in forming leaves, roots, tillers, and grain heads. The plant's development stage at any point during the season is affected very predictably by how warm or cool the season has been up to that point. This knowledge, combined with educated guesses about how the rest of the growing season will progress, can be extremely valuable information to the grower, who can then make more informed management decisions to include predicting the maturity/harvest schedule.

How a corn crop develops is affected by many factors: fertilization, rainfall, sunny or cloudy weather, hybrid or maturity group, etc. But these factors generally play second fiddle to temperature in determining when a corn crop tassels or is ready to harvest. Many years of observation have shown that plant development at any point during the season is affected very predictably by how warm or cool the season has been to that point. This knowledge, combined with projections about the remainder of the growing season, can sometimes be used to make mid-season adjustments in management and to predict harvest schedules.