Length of growing season is important in crop monitoring. While the values given in the map are averages, during a give year the actual season may be longer or shorter, which leads to crops being unable to complete their cycles, and usually to below average yields. This, again, indicates the areas with the highest potential, and those where unfavourable conditions are likely to cause most harm. Reference maize yields are also important for forecasting as one of the variables in yield function. In a food security context, it is thus useful to be well informed about the herd composition.
Relevant information is given in the map below.
Climatic databases must be assembled in all crop forecasting systems, since climate is the dominant factor in the variability of crop yields. In fact, the core of most crop forecasting models is a soil-water balance, which requires that crop water availability and consumption are known. Consumption depends on several variables, such as temperatures and wind speed. This is why agrometeorological data bases usually go beyond simply rainfall. Climate conditions sometimes vary significantly even over small distances.