Soruce: http://vasat.icrisat.org/crops/pearl_millet/pm_production/html/m4_4.2/index.html

Climatic Requirements for Pearl Millet

    Red dots indicate Millet growing environment

Pearl millet can grow in a wide range of ecological conditions and can still yield well even under unfavorable conditions of drought stress and high temperatures. It is generally grown between 40o North and 40o South of the equator, in warm and hot countries characteristic of the semi-arid environment.
Pearl millet is a warm weather crop and grows best at 20 to 280 C. Pearl millet is more tolerant to higher temperatures than probably any other cultivated cereal. These useful characteristics mean that it is finding a new niche in some unexpected places. The best temperature for the germination of pearl millet seed is 23 to 320 C. Pearl millet seed does not germinate and grow well under cool soil conditions. Poor emergence and seedling growth may result if planted before soil temperatures reach 230 C.
The optimum rainfall requirement of pearl millet ranges between 35 to 50 cm. But, pearl millet can be grown in areas, which receive less than 35 cm of annual rainfall. Prolonged spells of warm, rainless weather may be detrimental and may lead to reduced crop yields. At harvest time, dry warm weather is most suitable. Although pearl millet can respond to good moisture supplies during its growth, it is nevertheless one of the toughest, drought tolerant crops available. Pearl millet maintain its popularity in the regions where the weather is very unpredictable.
The ability of pearl millet to grow in drier environments is due to a number of physiological and morphological characteristics;

• Rapid and deep root penetration (root depths of 3.6m have been recorded);

• Has root system with well developed and specialized cell walls that prevent desiccation;

• Tillering capacity of pearl millet compensates any reduction in yield contributing components such as number of heads, length of the head, grain weight etc.