Adverse weather is the major threat to agricultural food production, primarily affecting plants during the growth phase, but also during storage. The weather conditions causing damage are: precipitation, which includes heavy rain, hail or snow; extremes of heat or cold; excessive sunshine and radiation; excessive wind; insufficient water due to lack of precipitation and ground water level changes; and insufficient or excessive humidity. Practical methods have not been found to assure 100% protection, and in developing countries there is often no protection at all. In such countries, whose economies may depend on a single crop or a single harvest, adverse weather is an economic and social disaster.
Serious droughts occurred in in 1972 in the USSR, the Sahel, India, South America and Australia. The weather and consequent food shortage was then considered responsible for the death of over a million people in India and Bangladesh alone.
Research in the USA reported in 1999 found that herbicide-resistant soya beans became stunted in warmer soils (above 45øC) and suffered from split stems, producing crop losses of up to 40 percent.