Typically from around June to October, this period is also commonly referred to as the 'hunger season' or the 'lean season'. The availability of food varies from season to season and may be severely affected by the weather, especially when this gives rise to floods, heat waves (droughts), and cold spells. Environmental degradation can increase vulnerability to these effects. The growing dependence on a limited number of crop varieties over large areas may amplify the effects of weather and pest damage. Climate change increases the risk whilst raising the challenge of accurate forecasting.
Fluctuations in food production can cause transitory hunger at local levels and impact the global food markets.